If you can't use sulfates, stay away from silicone. You need sulfates to remove it, otherwise it builds up on your hair making it increasingly brittle. If you've been using something with silicone in (won't be listed as silicone usually listed as something else so research ingredients) then you'll have to use something with sulfate as a one off to get it out of your hair.
Then stop brushing your hair. It may have been straight before but sounds curly now. Get a wide toothed comb, I don't mean the wider end of a normal comb, a proper wide toothed comb.
Comb your hair when it's got conditioner in and comb your styling products through, that's it, leave it be. If you don't use conditioner, start. Your hair sounds dry, which will make it frizz more.
Use some oil in it now and then whenever it feels particularly dry or becomes difficult to style.
You need mousse (lots, not a 50p size blob, a handful) and maybe curl cream too (small amount). I use mousse and coconut oil (from the world food section of supermarket).
If you use a hairdryer make sure it has a diffuser on it. Otherwise you'll get frizz.