Go with the most trusted exchanges. To find them you could look at reviews or just ask people on a forum (just like you did
![Grin](https://bitcointalk.org/Smileys/default/grin.gif)
) Currently, I use BitTrex, Cryptopia, and YoBit. I haven't had any bad experiences with BitTrex or Cryptopia. However, YoBit is a different story. I would stay away from it because their withdrawal rates are pretty high and their customer service, for the most part, is nonexistent.
Also, since it sounds like you're new to trading I figured I'd tell you this. If you're going to try day trading, start with smaller trades until you get a good idea of what you're doing. $10 and $100 trades are pretty much the same thing, there's just more money at stake.
Good luck and I hope this helps!