I have used artist's acrylics a bit, and found that often (but not always) the binders are too thick. When thinned sufficiently for miniature painting, they lose opacity. Sculpey is good for terrain and scenery but I wouldn't use it on miniatures- green stuff (Kneadatite) is the go-to epoxy putty for sculpting, but I find it gets a little easier to work with when mixed with Milliput.
Personally, these are my go-to recommendations on paint brands:
-Vallejo Model Color for basic colors. They're cheap, they come in dropper bottles, they have a huge variety of colors, and they're widely available.
-Vallejo Metal Color for silver metallics. I'm still experimenting with other brands, but nothing else has come close.
-Scale75 for bronze/gold metallics. There's also Vallejo's Liquid Gold range, but those are alcohol-based so a little trickier to work with.
-Army Painter for washes. In my experience they produce better shading than the Citadel ones- stronger shading with less tinting of the surface.