The first thing you need to look at is your bridge saddles. If they are sharp or have burrs on them you could use the thickest gauge strings and still break them. If that is not the problem then it could be you are useing too small of a gauge string for your style of playing. If you are a begginer, I suggest ten gauge strings. They are harder to bend, but help building up your fretting hand strength. If you have a hard attack, I know I do, then you will want to use an even thicker gauge. I personally use Ernie Ball Power Slinkys on my Jackson kv3. I almost never break strings. I use Clayton 1.52 picks, and use a lot of force. I really like that in your face distortion like God Smack or Obituary. If you are going for speed licks you might want to venture into the nine gauge strings, but the key here is to build up you hammer on pull off skills, so you are not hitting the strings so much with the pick. when you do hit the strings with the pick you want to glide on the top edge of the string so you can alternate pick at really fast speeds.

Hope this helps,

Sixx