We started with male guppies in a small tank, i do find they are not that hardy (as they tell you in the shop), i love my bristle nose plecs as they dont grow as big as the other plecs, i agree with Danio's, they seem hardy and are fun to watch. Platys are nice but they breed quite fast as do Mollies.
Before you decide on any fish, what size is your tank and what is your tap water like (hard, soft, acidic, alkaline?). That will narrow things down. Then you can decide what sort of thing you want, what sort of decor you want etc. That will narrow it down more.
You'll need to set up and cycle the tank before you can add any fish. That might take up to 6 weeks. Choosing fish is the very last step!
How big of a tank can you fit in? The absolute minimum is about 45 litres for a single specimen (ie a male betta) or 60 litres for a shoal of small fish (one species). If you want more than one type of fish then I'd go for something around 80-90 litres to start off with.