I just bought a whole kit from Testors that had all the basics to get started, a tube of glue, glue for attaching windows (which can, in a pinch, make windows too), a knife, some really cheapass nylon brushes, and flat, military color enamel paints. According to their catalog, it’s part #9160. I think I paid about $15 for it.
It’s got pretty much everything you’d need to make military models. You might want to go to the hardware store and get more thinner, because the tiny amount they give you doesn’t last long.
I haven’t seen any suggestions for this, but one thing I use a lot is rubber bands, clothespins and those big metal paper clip things (I’ve heard them reffered to as binder clips). Use as many as will fit when gluing two things together. I use alumninum foil between the rubber bands and the model plastic, because some rubber band material can react with the plastic and melt it, also, it keeps the bands out of the glue.
Once upon a time, I had a bottle of the testor’s liquid glue that worked well. I’d never had one before that worked, and never had one after. I suspect that they go bad (active ingredient evaporates off?), and go bad pretty quickly, and I just happened to get lucky once and get a fresh bottle. I wish it did work better, because I really hate the little stringy things that come off the tube-type glue.