Picking Your Betta: Vibrant Color, Full Fins, No white spots, Clear normal eyes, flares are you or a neighboring betta, swims normally. Also, pick one out that just "clicks" with you. Remember females can just have as much personality as a male.
Tank Prep: Minimuim 2.5 gallons for a permanent home. Get a 5 gallon if you want tank mates, such as shrimps. Get a good water conditioner to keep your fish from getting poisoned by things in the water. Ideal temperature for a Betta tanks should have a temperature between 78-82 degrees. Silk plants and/or live plants are your best bet. Decorations with smooth rounded edges are best, as well.
Food: I feed Hikari Bio-Gold, but I have found New Life Spectrum is also a good food. As well as, some frozen foods including Daphnia, Bloodworms, Brine Shrimp, etc.