The Importance of Priming
You picked out your first miniatures, congratulations! But now you're not sure what to do first. Your first painting step should be priming your minis. Why prime? Well some minis are of a material that paint doesn't like to stick to. Primer gives you a nice coat to paint off of. Not only does it give you a even base coat to work off of it also makes sure any of your minis that are shiny plastic are now matte. Some paints, such as The Army Paint Speed Paints require a white base coat for the magic of the multi paints to work. Also if you have a 3d printed minautre a primer gives you a good starting point to work on. White primer is needed to make light colors (such as yellow or orange) to pop nicely. Paint likes to stick to paint; it's easier to prime your plastic minis once or twice than to spend numerous coats of your other paint layers trying to get it to stick to the bare plastic.
Now days some miniatures, like certain Wiz Kids minis, will come pre primed. That is great but many miniatures are not primed and need a primer coat. To the left here are some of our primed miniatures here at Dungeon Fox Chronicles. I (Fox) use the citadel can primer as it is easy to come by in hobby/game stores and is relatively easy to use. In the picture the tiefling waitress and the goat lad were primed with citadel Wraith bone. The Grey minis are primed by my Wolf who uses the airbrush to prime miniatures. He uses a variety of colors to prime. Dragons are primed in their color, snakes are usually primed green and other pieces can be done based on what will look good with our dry brushing. I tend to stick to white or black depending on the piece I'm working on as they are simple easy color. Priming in black gives great shadows and crease lines to your miniature. Other minis are pre primed (such as the wiz kids minis in the picture) and do not need another primer coat unless you need to touch up around file lines.
The first step I do when I get a mini is take a file to take off any mold lines for plastic minis or in the case of 3d printed minis, I need to clean up the rogue filaments. After I use the files it can rough up the materials that the mini is made of, and a primer coat can give me a more cohesive surface after any cosmetic touch ups. Also know that primers can be used to fill in fillament lines more to give a smoother look. If you have a 3d printed mini that needs liquid green or just has deeper lines in between the fillament rows, primer can help cover them up before painting.
Some plastic is too shiny
These Reaper minis I got from a Kickstarter is too shiny of a plastic to paint. It doesn't dry well on this plastic and runs. If your plastic shines in a light you should consider a base coat to make sure you can paint your minis the way you want them to. If you paint these plastics without a base coat you also risk your paint rubbing off.
Covers up the Green
Some miniatures are large and need to be glued together. This can cause gaps between the pieces requiring liquid green or a filler putty to make the miniature one piece. A primer will cover the green and will allow you to paint over the areas without the green color showing through.
What Happens if I Don't Prime?
These are two really great examples of what happens to minis that aren't primed. The paint didn't stick to either of these and had to be chemically cleaned off so a primer coat could be applied. The paint wiped off, dyed the plastic but didn't stay the actual color and overall just needed to be redone.
When to NOT prime
Some miniatures are clear on purpose such as the ones featured here. If the mini is transparent for gems, spells or the like you do not prime them. Primer would ruin the transparent effect they have. These paints have specific types (shades, washes, quick paints) that can be used to give the transparent a bit of color.