get a good spray primer and a good detail brush and just have at it
use water based paint at first so you can fix anything you mess up. Walmart has some in the hobby section. water based latex. Do not go expensive at first just some nice standard hobby brushes will work.
these brushes at walmart work good. It just takes practice and patience, and using water based will let you go back and fix it once your better at it. There are tons of ways to make it look better like shading and using washes but those too take practice. Starting off just grab the cheeped miniatures you can find and experiment.
spray them with a good primer. I would get grey to start. white and black have their uses but for just starting and experimenting get a grey primer. once you get it primed use your main color and paint a light coat on it. doing more light coats is always better than one thick coat. that can clump and run. to make weapons look nice do a coat of black under it then experiment with a dry brush of silver or gunmetal. Dry brushing is a pretty easy technic. just put a drop of pain on a paper towel and get a clean dry brush. just get a little paint on the brush them wipe it off on the towel where it doesn't even seem like it had paint on it. then just lightly brush it over the black parts like weapons and such
thie gives it a nice gunmetal look.
use a hobby knife or a toothpick will work to get paint that may have run over. just scrap it off lightly
it is worth it to get some awesome looking miniatures once you learn the basics.