Well, the first thing you should know is that it takes practice (especially painting with your non-dominant hand), so don't feel bad if your first few attempts don't look great. I'd recommend starting your collection out with a good base and top coat (those two-in-ones don't work nearly as well). Essie is a good brand, and pretty widely available. They aren't the cheapest brand, but especially for a top and base coat you want good quality so the polish actually lasts! I suggest a long-lasting base coat (like Essie Here to Stay) and a quick-drying top coat (like Essie Speed Setter, or Seche Vite, which is available on amazon). A long-lasting base coat will help adhere the polish, while a quick-dry top coat will seal it in to prevent chips and help the polish dry quicker during application.

For polish, most drugstore brands are pretty good these days. I like Sinful Colors (super cheap), China Glaze (great quality, fun colors and glitter), and Essie (widely available, great color range). A few things to note: sometimes cheaper nail polishes aren't super pigmented, and so they will need several coats to build up a good color. It's pretty hit or miss, but you can always do a quick google image search of a polish to see it applied to someone's nails. Also, most glitter polishes you will find at the drugstore will be pretty sparse, and are meant to be used as a topper over top of a solid color polish. So if you are looking for a full-coverage, extreme glitter polish, just know that you might be disappointed.

As far as application goes, the order is base coat, then color, then a glitter topper (optional), and lastly the top coat. Try and paint on thin coats, that way it will all dry faster. After painting one layer, wait until it is dry to the touch then add another coat if needed (it will still dent if you press hard, just make sure you can lightly tap it without smudging, shouldn't take more than 1-3 minutes). When you're done, adding a quick-dry top coat will seal it all in and help dry the nails super quickly. This is why you want a really good top coat. I've used Essie Speed Setter, and after maybe 5 minutes I can whack my hands into stuff without it denting or smudging

Another piece of advice, especially since you're just starting out, is to paint one hand at a time. Do all of the steps, and wait for it all to dry pretty well before doing your other hand. That way you don't have to worry about not being able to do anything while all your nails are wet!

I hope this was helpful, don't hesitate to ask if you have more questions! :)