Doug , from the looks of it, you already have the basics. Now here, I know I'm gonna get "Jumped on " by a few of the ALL KNOWING, ALL DOING here .
1. determine what kinds of modeling you want to do .
2. Determine what scale you PREFER to work in
3. ARE YOU A SCRATCH BUILDER ?
4. if the answer to question 3. is yes , you need a few more things . HOWEVER, if you're a Kit builder as a good number here are , I'd say you're well on you're way.