Primer...Priming...

Personally I use Tamiya's Fine Primer in a rattle can, but many here use Krylon, available at most hardware stores or dept. stores that still have hardware sections. As they aren't designed for use on styrene kits, I would advise a light hand when applying so it doesn't obscure details.

I use rattlecan primer, either Krylon or auto parts store primer.  Both are somewhat rough when they dry, so they need sanding with fine wet-or-dry paper, but are good primers and much cheaper than stuff from hobby shop.

thanks guys.. i always like to save a buck or two and still get good results. ha

Ethan

Solution 1: use another brand of acrylic. MM acryl is notorious for the poorest adhesion of hobby acrylics. It requires a very clean surface for application.

Solution 2: learn to get the plastic clean before you paint with an acrylic. That means a wash with Simple Green solution, Windex, a surfactant cleaner, or a wipe down with 90% isopropyl or denatured alcohol, and not handling it with bare hands after that until the painting is done.

It is not necessary to prime under acrylics, even MM Ack, especially not with an enamel primer. All you need is a clean surface. The only reasons I prime are to search for surface defects and under specialized coatings that specifically require it. When I do prime, I use Tamiya Sky Gray acrylic.

Ah the great primer debate again!  I always prime regardless of what kind of paint I will be using, or what I am spraying on (plastic, resin, metal, etc.) 

I have always felt this gave my paint more adhesion to the model, especially when masking so paint will not lift off.  Secondly, a nice uniform primer coat lest me spot flaws or areas which need a bit on extra work before painting. 

I use duplicolor sandable primer, available in most auto parts stores.  It has a very fine mist, is consistent, and....sandable!  I typically use grey unless I am spraying a tan vehicle, then the red-brown gives a bit of pre-shading to the kit.