After you have gotten at least the basic equipment you need (see above) and cycled (see above), easy-care fish include many tetras, like head-and-tail-light, black neon, and glow-lights, and no doubt other smallish tetras. In my local pet store (been there +20 years), in the fish section, they are in the "easy-care/beginner fish" wall of tanks, and such fish tend to be inexpensive. They are egg layers, and the eggs are often eaten so you don't have to worry about extra fish you are not ready for as you might have to with live bearers.
I recommend starting with easy, beginner fish as they are usually hardy enough to withstand many beginner mistakes and help you get to the point where you are confident about expanding your lifestock and spending more $$. Such fish can also be full of personality and fun to watch.