Removed.

What exactly are you asking?
Trading a Steam Key for a Steam Key?
It's mostly safe to do in the Trades Section.
Just check the trader's profile prior to trading.

Check user feedback (SteamGifts feedback, not feedback posted on profile as it is worthless)

User enhanced steam so you can directly check steamgifts/steamtrades/steamrep pages.

best is to do some low trades first to built up your own rep
And indeed read the fb on the profile of the person you are trading with

Start small. Don't try to trade for a Fallout 4 Deluxe GOTY Extra edition right form the start. Build up a reputation on trading with cheap keys.
Be reasonable. Just because a game is listed for 30 dollars in the store, it doesn't mean you can use two keys for that game to buy a 60-dollar fresh release. For example, Planetary Annihilation is listed at 30 dollars, its real market value is around 30-40 cents.
Don't be greedy. A small profit is expected if you are selling, but nobody likes people who want 100% profits on their products. Unless you are a company called Apple or Bethesda Softworks. In this case they expect you to be as greedy as you can.
If you want to trade Steam keys for Steam keys, use the barter.vg web site to set up deals. It has one of the most reliable feedback systems and is built to make key for key trading as easy as possible.