TF2 Trading is pretty easy.
The Item drop system drops items, that you can turn into metal.
1 Scrap Metal = 2 Same Class Weapons
1 Reclaimed Metal = 3 Scrap Metal
1 Refined Metal = 3 Reclaimed Metal
Here's the universally accepted price sheet for most every item in TF2:
http://tf2spreadsheet.blogspot.com/
A quick rundown of basic current TF2 pricing:
1 Key - 2 Refined + 2 Reclaimed
1 Bills Hat = 10 Keys
1 Buds = 2 Bills hats + a little more (a few keys)
1 Max Head = 2.5 Buds (2 Buds + a Bills + a key or two)
Here's a handy guide for pricing Unusual Hats:
http://www.tf2unusualhats.com/
Using Real World Money (paypal mostly) to get things like Keys, Unusuals, Buds and Max Heads. Keys in the MannCo Store are $2.49; however, you can routinely buy them in bulk from traders for $1.45 a piece.
Before you sell or buy from someone, make sure of the following:
Know who you?re dealing with:
This is done by checking the person with SteamRep:
http://www.steamrep.com/
Here's a SteamRep profile of someone who tried to scam a Max from me:
http://steamrep.com/?id=76561198061204968
Need to find someone's Steam ID:
http://steamidfinder.com/
Watch out for scammers:
(I have a couple of Max Heads and some Buds for sale right now; I've been contacted by 4 scammers so far. )
They will imitate well-known and trusted traders. They will make their Steam Community Profile page look exactly like a well-known trader, sen you a trade request, and (if you don't do a quick background check) they will take your items and leave you with nothing. Checking someone only takes a moment, and it should be a mandatory part of your trading practices.
Here's a quick example of a scammer:
User *L-M* NOnoS' B. KEYS 2,33REF is a well known, high volume trader. He has a SourceOP rep thread in the hundreds. Someone has copied his steam name, his profile, and tries to trick people into getting their items by asking them to go first in a transaction, based on his enourmous rep status:
Quick things to always check for: his Trade Status is
BANNED, I was the only friend on his list, and he only has a few games on his account.