RECC.->*-Install lightshot (Screening tool used for capturing desktop images In case you need to report fraudulent activity from the 2nd party).*

If you are sending paypal tender:
-Use a certified/trusted middleman ( Ex. Wrath)
-Make a statement as to why you are transpiring via steam chat toward the seller
-Confirm the seller gave the items to the middleman
-Send the money to the seller, then have both parties confirm the seller received the money to the middleman.
-Middleman exchanges the goods to the buyer (you)

If Not using a middle man, the seller should have a reputable trade background eg. Source Op rep

If you are receiving the Paypal tender:
-Use a certified/trusted middleman ( Ex. Wrath)
-Make a statement as to why you are transpiring via steam chat toward the buyer
-Make a statement prior from making the transaction stating that the person will not chargeback.
-Send Middleman your items for trade
-Confirm Paypal tender was received. Alert the middleman once confirmed.
-Middleman sends goods/items to buyer

Highly Recommended
Do Not trade players that:

-Have private profiles
-No/little games/time
-Young account (Should at least be 1 year old)

Caution players that: (exceptionable)
-Do not have any acceptable trade reputation (Steam profile comments do not serve as proof of identity for a trade)
- 2 or more banned users on friends list
-No friends
-Low steam Badge level

Middlemen list: http://steamrep.com/list/M
Professional SR Guides: http://forums.steamrep.com/forums/steamrep-guides.22/
 
Never go first.

In order to have a successful and smooth trade, both parties must trust one another before beginning the process. Otherwise, the entire negotiation will crumble in skepticism and the deal will not be made. That's why there are safety essentials that help prevent anything from going wrong.

However if ever in doubt, and you feel you cannot trust the other party, do not continue and decline the trade offer.
 
In order to have a successful and smooth trade, both parties must trust one another before beginning the process. Otherwise, the entire negotiation will crumble in skepticism and the deal will not be made. That's why there are safety essentials that help prevent anything from going wrong.

However if ever in doubt, and you feel you cannot trust the other party, do not continue and decline the trade offer.
Ive never trusted anyone. And I never got scammed