well i can help you with that. i do a lot of fish stuff (I am a loser i dabble in everything)
you need 1 gal of water per inch of fish.
10 gal tank is cheap and a great starting size.
you need stress coat, fish food (lol), if you are using tap or well water salt (bought in the pet isle), cycle, and the big bang PRIME (which takes out nitrates chlorine amonia etc)
follow the directions on the bottles and your tank should go great. depending on your fish I would recogmind taking 10-20% of the water out a week and replacing it with 1-2x a year doing a entire tank scrub down.
I do a lot of 'experiments' with fish putting different species together and the like, so i am pretty good with telling which species can go together and whatnot. though they say betas like small bowls that is bull. I put mine in a 1-5 gallon tank depending on my resources at any given time. give only 3 pellets a day as they will either not eat them or will over eat the pellets. old pellets in the tank will turn into mold (gross)
Good luck
Let me know if you have other questions. petco/smart are GREAT places to talk to about starting tanks too,