Read the link in my signature about cycling - you don't just leave the tank for a month. That doesn't do anything. You need a source of ammonia and some test kits.
You can think about fish later but if you are looking for suggestions now, tell us what sort of tank you want... I mean do you want a community, species, active, peaceful, boisterous, aggressive, livebearers or any fish you like/son't like more etc... Also, what substrate do you have and do you have lots of live plants? What about floating plants? Rockwork/other ornaments? What is your water's pH?