Very new to handguns

I just recently turned 19 and took the CCW class and also applied for it. I'm very new to handguns, but have been around long guns for a while. I live in Missouri. Seeing as I'm 19, getting a handgun to carry would be a challenge in itself and I believe I'm limited to private purchase on that. My second thing, which may not have as clear an answer, is caliber. I was told to carry the highest caliber you still shoot well. Basically, I'm here asking if anyone has a solution to narrow down my choices as I'm finding it very overwhelming as a novice. via /r/CCW http://ift.tt/2aCqWBO