This question was posed at another discussion board where I am a member and thought it was something that should be addressed as the answers given were generally not very specific. The following is my response and I decided to post it here because this seems to be a very common question for gamers and some collectors on many forums that I visit...
I use either Model Master Clear Coats if painted with Model Master paints or Vallejo Varnishes if painted with Vallejo paints. Since I no longer use any other paint product, this makes it easy to achieve consistent results that I am very happy with. I have had many models used in catalogs over the years and these two paint "systems" have been part of the key to that success as I no longer struggle with Krylon, Humbrol (Humbrol actually wasn't bad, just can't get it anymore and don't know if they're doing acrylics or not) or any other product that has not really given me the results that I want.
Remember, Model Master and Vallejo are two paint lines that are specifically formulated for models and as such they have a very fine pigment that other non-model specific paints will lack. Oh, and I haven't used oil paints now in well over 10 years. If you have a model to paint that is made of something that is questionable for acrylic paints, then adjust your primer accordingly and use the acrylics to do the actual painting, then you can still use the varnishes or clear coats with the same success you would normally have.
I really can't say enough about these two paint lines as I continue to see a great many modelers struggle with painting issues. I guess I settled on these two products because all of my plastic model buddies (IPMS contest winners) generally stuck with one paint line to complete their entire models and I figured if that concept was good enough for their award winning models, it should be good enough for my gaming miniatures. It has really made a huge difference in my painting and with all of the models that I and my friends have done over the years for catalogs and such, it takes away some of the stress because we can count on consistent results. It really is now all about our techniques and skill and not the paints or finishes.
Oh, if you don't want to use an airbrush, I would also recommend Reaper Pro Paints in addition to the Vallejo line for brush only painting, but use Model Master Clear Coat to finish them if you aren't using Vallejo paints.
Happy Gaming!

