The art of the deal is not something that can be covered in a single article, but there are a lot of small actions you can take that will make your trading endeavors go smoothly. The most important thing to remember about trading is that, although most people assume that it's all about matching value, it's actually much more about psychology. I've touched on this before, but I'd like to outline a few specific strategies here today.
I'll Show You Mine if You Show Me Yours
People can sometimes feel threatened by the "approach". We've all felt the unpleasantness when someone with three giant binders gruffly approaches you, breathing down your neck, and asks "Trades?" These people usually lack basic social skills, and don't realize they're intimidating people away from trading. While I'm not here to teach basic social skills, I can give a few pointers.
Don't slam down a stack of binders. Have everything nicely organized into separate binders and take them out one at a time, once your partner has agreed to trade with you. I find it's best to have Standard separated from Extended separated from Legacy. I also like to have a binder for foils and promotional cards, since people who value these highly don't want to sift through a book full of non-foils. Having your stuff well-organized lends you a lot of credibility, but it also lets you just show off the inventory you want to show off, and won't intimidate people like a bunch of overstuffed binders and a hard-sell attitude.
People Spend More When They're Smiling
The next step is to be polite, accessible, and kind. I know, that's a tall order for some people, but trust me, it's worth it. As opposed to just walking the room with a suitcase, pointing, and asking "trades, trades?", here's my suggestion. First, smile. You're playing the game you love, so be happy. Most hardcore traders act like they're working, and the attitude is not conducive to casual, fun trading. If people believe you are a shark, they'll swim carefully in your waters. Sharks don't smile except to show their teeth, so act like you're having a good time.
Secondly, don't just bark at people. Engage them in conversation. People don't like feeling like lambs to the slaughter, waiting for some shark trader to come rip them off. I do this when I go to flea markets, garage sales, or trade Magic. There's always a little anecdote that comes along with my trade, and that makes people more amenable to chatting with you in general. You'll be seen as human, not a trade shark, and even when you are being a real stickler about prices, you'll have an existing rapport with the other guy so it's not like you're just some jerk arguing over nickels and dimes.
I'll approach a person who has a binder out, or looks as if he might have one. I'll ask for a specific card or type of card, for example, "Hey, do you have any trade stuff? I'm looking for some oddball cards for EDH." This is usually true; I don't really suggest lying to people, but that's a personal choice you'll make. I like leading with the "oddball EDH cards" phrase a lot, because weird foils, alterations, and other such rarities are what I really love finding at big events. It also lets people know you're not just a shark. This way, when you start working a "value trade", you can also incorporate EDH stuff to take the "edge" off. After setting the tone of the transaction, I'll start talking about what I'm looking for. This helps get people chatting and feeling comfortable, but it also might remind them of some other cards they have for trade you might want! I love to tell people about my Rare-B-Gone Cube, which is over 1000 amazing powerful cards, all of which are common or uncommon. I explain that I'm trying to foil the Cube out, so if they have a junk binder, I'd like to raid it.
This process takes a bit of extra time, but it also makes a huge difference in the trade. People who like you will give you a better deal, and I guarantee that no one who lugs around a suitcase, doesn't bathe, and just barks "Trades!" at people is well-liked when they are acting that way. Even if I don't make a deal, most people enjoy trading with me because I'm just plain friendly. We might even sling a few games of cards if I need a break from working the floor. It's good EV, it's fun, and it's the human thing to do.
Mister Manners, or, Mama Would Be Proud
Once you have their binder out and are engaging them in conversation, the next thing you should do is find out their trading etiquette. I have my binders neatly organized so that people can easily find what they need, but most people sadly do not. Because of this, I will ask people to take a flip through to make sure they can find something they want. This is never an issue, because I have almost everything. However, it's really a nice way of saying "don't pull out every friggin' Planeswalker I have until I see that your binder isn't stuffed with garbage rares and some commons". As you begin looking, upon seeing the first card you want to acquire, ask if you can pull out what you want and say "go ahead and you do the same". It's helpful to guide the process because you can set the pace, tone, and really tweak a lot of the psychological factors in your favor. Now they are pulling out cards, and they are invested in the trade. Having a stack of cards that are about to become yours is a powerful feeling, and I reinforce that by making it clear with my actions that I'm presupposing the trade. I'll handle the cards I want as if they are my own, sort them how I want, and make it clear that they're "mine". Its amazing how these little psych tricks really add up and work in your favor. They're not always necessary, but they're always helpful.
Once you have the cards pulled out, you need to make sure you're on the same page regarding valuations. Jonathan Medina, mister Pack to Power, is an absolute expert on this but here is the gist. Figure out how they price their cards. Do they use a major online dealer? An ancient issue of Scrye? Do they use Ebay? Are they getting realtime data with a smartphone? All of these things tell you volumes about how the rest of the trade will go. Knowing that Dealer A sells older cards for more than Dealer B is helpful, especially if your trade partner is going by Dealer A prices and you're trading older cards! Don't argue over his valuations even if you disagree with them, because that sets a contentious tone to the trade. Instead, just let him value his stuff and then at the end, politely disagree where necessary. Sometimes an absurd value system can help you gain more value.
When discussing a card's value, be sure to leverage every possible angle you can. A card's value is not immutable. In my store, I have an awful lot of Day of Judgments. I pay poorly for them, and even tell people not to trade them in, as they can get a better deal from someone else. This usually backfires for them, since they seem to appreciate the honesty and will trade them in for almost nothing when I'm upfront that it's worth more than I can pay. This principle works because people don't like to feel that they're being "taken", but if they know the deal and why it's slanted, they will have the necessary info to justify it. People will overpay for anything if they can justify it. It's the reason people pay retail price for something; they can order online and get it in a week, or they can pay retail and get it now.
Once you have the cards appropriately valued, you just start comparing values. I find it helpful to find "sub-trades" within the trade, and set those aside. For example, "Card A and Card B are fair for Card C, right?" If he agrees, set that aside or just execute that trade right then and there. It's much easier than doing a big blockbuster. Once you have the trade basically squared up, try to make sure it's slightly in his favor. Then you can get to the fun part.
Give Me Your Tired, Your Weary, Your Crap Rares
I love crap rares. So hard. Not only do they have the potential to be shooting stars, some people consider some very good cards "crap rares". The classic example is Elvish Piper. This card is $5 all day long to casual and EDH players, but a throw-away to tournament-goers. Once you get to a deal that's not quite fair for you (and you should always aim for this, by adding more cards if necessary), ask if you have some junk cards he can throw in to level it out. You can really get tremendous value here, since your trading partner will probably throw in tons of crap rares just to dump them off. You grow your inventory and increase the chance that you pick up the next random shooting star. Get as many of these as you reasonably can, and just go from there and make the trade.
Always be polite the entire way through, and make a point to make an impression. If people give you a reputation for being a nice, fair trader, you'll get more business. Thank them for their time, even if you couldn't make a deal, and move on to the next trade. It quickly becomes a habit, almost like a script, but don't feel bad if it feels rehearsed. It's just something you'll do a lot of, and more or less, you'll be saying the same basic things over and over again anyway. In addition to spotting good cards to speculate on, just making a few bucks on every trade by being savvy is a great way to add value to your collection and begin the process of making this game pay for itself!