A regular drawing tablet like a Bamboo or Intuos (or another comparable tablet by another brand) works just as well as a tablet monitor like a Cintiq (or, again, a comparable tablet by another brand).
No tablet will make you magically amazing. It all depends on your own skill.
(that said, there may come a point where you feel like you need to switch from a regular tablet to a tablet monitor, but personally I'd recommend going with a a regular tablet first and building your digital skills on that. You can invest in a nice monitor tablet further down the line, if you feel the need to. But there are plenty of professionals who use some cheap, off-brand regular tablet and do wonders with it. There's a guy named Frenden who you could take a look at, he reviews tablets of all sorts. Just google "frenden tablet reviews" or something and you should find them easily.)