I completely disagree with Frank about craft paints.
once you factor the once per ounce cost.
In theory this is true. You won't run out of paint, though. I'm still using 17 mL droppers I bought years ago. I've painted hundreds of miniatures with them. What you'll get from craft paints is low quality, heavy pigment that will cover details in an elastic film that may then crack apart. The extra money for quality paints is well spent.
When painting, always thin your paints. Using craft acrylics does mean you'll have to do a couple extra coats of a color. Notably red.
Thinning your paints is a poor substitute for getting into the habit of keeping your brush wet. A brush you clean often will last longer, it will prevent paint from flowing up into the ferrule whereas thinned paint will be attracted to the ferrule, and you won't have to do as much experimentation with finding the right consistency.
I wouldn't recommend enamel paints at all. I use several brands of acrylic paint and I'll tell you what I think they're good for.
Mostly what I use is Reaper Master Series for wet blending. Those paints are pretty good if you're going to be painting in layers (and you probably will to begin with), but they can't really be thinned because they're designed for wet blending.
Reaper Pro Paints are a different paint, and you can layer with them just fine. They come in pots instead of droppers, and like Citadel pots they are prone to drying out. They're also a hassle to mix because there is no dropper. You get a lot of paint for the price, though.
Vallejo Game Color paints are the other end of the spectrum from Reaper Master Series, they have a thick pigment that's good for layering. You want a thick pigment for colors like red and yellow especially. I don't thin my Vallejo colors, or any colors, I just keep my brush wet. But if you don't do either of those things, Vallejo can go on a little clumpy due to its thick pigment.
One important thing is that Vallejo colors do not come with agitators. The pigments can separate and you can wear your arm out shaking them back together. A good solution to this problem is to buy volcanic beads and put one in each of your bottles, so they mix with just a few shakes. You can get them for cheap
here
Another brand I use is Privateer's Formula P3 line. The major difference is that P3 uses a fluid pigment instead of small grains suspended in a medium. That means it can be thinned without losing pigment, and it goes on over black much better than the other paints. The P3 Armor Wash is probably the best wash I've ever used.
Also for layering, Andrea Color has assortments of shades of colors that are hard to mix without losing tone, like red. Those are a little more obscure, but if you find you're unhappy with your red highlights, that's one of the best solutions out there.
Generally regarded as the best brushes for miniature painting are the Winsor & Newton Series 7 brushes. I think every serious miniature painter visits this page at some point:
Winsor & Newton Series 7 Kolinsky Sable Pointed Round - BLICK art materials
A size 1 brush is almost too large for miniature painting, so go for the 0 and smaller brushes. Reaper sells even smaller Kolinsky Sable brushes, down to I think 40/0. A brush that fine is suitable for painting a glint of light on the pupil of an eye, to give you some idea. Yes, people really do that.
You're going to want to use different brushes for your metallic and nonmetallic paints. Metallic paint is full of little flecks of metal or mica that tend to stay on a brush, and then it can come off with a nonmetallic color. Once you use a brush with metallics it's potentially ruined for other colors, and you don't want to find that out the hard way with a $40 assortment of Kolinsky Sable brushes.