Well, if you're selling something on epvp, you have to use "The Black Market" that's the trading section. This is where people sell/buy stuff. Once two people agree on buying/selling something they do it on their own or with a middleman.
Doing the trade by yourself can get you scammed if you have a buyer that's not exactly trustworthy. See the thing in your(and other people) stats called "The Black Market:
0/0/
0"? Green numbers are positive trades, red are negative, you can click on them and see comments and find the best buyer.
Doing a trade with a middleman is safer, you give the account to him, the buyer gives him the money and he does the switch. Find a middleman from this list (that does dekaron trades and find the best price for you)

No middlemen are official therefore eltepvpers holds no responsibility if you get scammed.
If you're selling an account you need:
1) The account, it's always good to have some screenshots of the character (without any names), bank, gear, skills and stuff like that.
2) The email with the "Welcome" message, that's the email that was used to create the account with, no one's ganna buy your account if you don't have that.
The worst case scenario is that you sell your stuff to okaygoods (google that). They boost the price you want at about 40~50~80%. (Let's say that you want to sell an account for 50$, they'll sell it for 90 and give you 50). It's not cheap, but they won't scam you.