Newb Paint finish question

Its not necessary but it helps resist fingerprints in case you wanna transport it to a show or something like that.  Some paints by their nature are have a satin finish and you don't want the final result to have satin and flat finishes together you want an dead flat finish if your talking about AFVs.  Technically you should use a 'matte' finish since that's a dead flat finish.  The Krylon I have still has a little sheen to it which is why I'd say use the MM Acryl Flat b/c the Krylon isn't designed for scale models.  

As far as a pigment fixer goes you I usually use Future floor polish.  You can use mineral spirits, diluted white glue or a flat varnish to hold them down as well. 

If you apply pastels without a 'fixer' they'll blow off when you apply the final coat.  I've used MM Acryl flat & gloss to finish my models.  I use Future now for gloss coats and Krylon Flat for flat coats.  I may go back to MM Acryl Flat tho.  

Acrylic finishes are what alot of people use, the only finish you need to be wary of is if you use a lacquer top coat because it can attack the paint underneath, esp acrylics if they haven't cured properly.  You should be fine with any type of acrylic varnish to seal your work in.  Thats what I would recommend.