Trading in MM2 is how you get the items you actually want without spending real money. But it's also where most people lose their best stuff. Know what you're doing, how values work, and the most common tricks, and you'll come out ahead every time.
Trade requests come from the player menu. Both sides put up items, both have to confirm. Nothing happens until both hit accept. That sounds simple, but the scams live in the details — swapping items at the last second, fake duplicates, and promises of items they "donate" after the trade (spoiler: they won't).
MM2 doesn't have an official value system, so the community runs its own value list. Knives and guns are ranked by rarity, demand, and availability. A common knife might be worth 1, a godly could be 100 or more. The value list updates regularly — check it before every trade, not when you remember to. Values shift fast when new items drop.
The item swap scam is the oldest trick in the book — they show a godly, then swap it for a common at the last second hoping you don't notice. Always check the final confirm screen carefully. Then there's the "trust trade" where they promise to give your item back after you lend it. They won't. Never trade items you're not willing to lose. If a deal seems too good, it's a scam. Period.
Collecting instead of trading? The Collectibles Guide breaks down rarity tiers and how to find rare items. The Knives Guide has the full knife list with values.