|Don't skip the prep work! I've tried painting without cleaning or priming and it just makes life harder in the end.|
Things you'll need:
Razor blade/hobby knife/sandpaper/file - the first thing you do with a miniature is clean up any flash or mold lines, the line where the two halves of the mold met and some of the material (either metal or plastic) extruded out a bit and it looks ugly. trim it off until it looks tidy.
Toothbrush & dishwashing liquid - the figure usually comes with some mold release agent (oil) in the crevices, and also hand oils from your handling above. You want to get rid of this so that your primer/paint will stick well to the figure. a bit of dishwashing liquid and an old toothbrush works nicely here. I actually use my powered toothbrush with an old brush head cause it's faster for cleaning lots of figures at once.
Primer - Yes, this is good idea.
Color choice: black, white, grey. Black takes less paint for a solid coat, and mistakes are less visible. White is good for brighter colors in your final paint scheme. Grey is a good balance between the two. I usually use white or grey. You may not need solid coverage, depending on how good the acrylic paint you end up using (more on that below).
Primer choice: any spray primer works fine, even automobile primers. Just make sure it's actually a primer. spray is usually great and fast but doesn't work well in extreme cold (like when it's snowing). In this case Gesso is a alternative (found in art supply stores). This is a goopey, paint-on primer but has this magical shrinking ability as it dries, so you don't loose details. Some people like to dilute with a bit of water just in case, but i use the Liquitex brand white straight out of the bottle with a drop of black paint to make grey and it works pretty well. Also sold in white, grey, black, and clear (never tried it). Takes 24 hours to fully dry, but in cold weather it's the best primer method. More info on gesso.
Brushes, pointed round, for watercolor, size 0 or 1 for most of your grunt work, size 3/0 (or 000) for details like the eyes. Although natural, kolinsky sable brush are awesome (and something you should get if you like this hobby), for painting a single figure quality synthetics actually work just fine (like golden taklon or white taklon). Just stay away from anything Camel hair. if you have a slighly larger brush, that's old and worn out, it's good for drybrushing. or get a flat/bright/filbert brush for dry brushing (anything cheap will do, again except for camel hair). Drybrushing makes it easily to paint the highlights. also good for metal (use a black base coat then silver dry brush). More info on brushes Drybrush article and another Drybrush article with pictures!
Acrylic hobby paint - here is where it can get expensive. cheap walmart craft paint costs like $1 each, but they are thick and cover terribly. Acrylic paint for miniatures specifically are formulated with a much finer grind of pigment, denser amount of pigment, and thinner, smoother paint flow. But they cost like $3 or $3.50 each. My recommendation is to figure out what colors your base coat are going to be and get those in miniature paint. For details, shadows and highlights use the cheap craft paint. The reason being is trying to get a solid coverage using thinned down craft paint is really annoying, you need like tons of layers, whereas good miniature paint covers well in 2-3 thinned layers. For example for a forest elf, maybe get some medium green, leather brown, skin tone, black, white in good miniature paint. Then for shadows and highlights mix up your own dark and lighter green, or buy the cheap craft paint. The other hard part is miniature paint is usually only found in specialist hobby stores that cater to miniature figures/gaming like a Games Workshop store. Typical brands are Games Workshop, Vallejo, Reaper, and my personal favorite Privateer Press (P3 line). P3 has Excellent coverage and dries really thin! The art of thinning paints Painting eyes
There are other options besides acrylic, but acrylic has the advantage of easily thinned if needed (just add water) and easily cleaned (water), and non-toxic. Enamels aren't so easy to use. You CAN get acrylic paint from art supply stores like liquitex, but usually they are really expensive and really thick (need to be thinned down). But hey, feel free to explore, maybe you could try water-color paints or gauche or something. It's your project so do whatever you want and have fun!