How did you keep your betta in the past? They are very easy to keep, especially if your tank is filterered and larger than a little cup. Make sure you select one that seems healthy and active and make sure it likes the food you give it (some of them are picky about which kind of betta food they like, mine will only eat one brand of pellets and will look at nothing else. I had one in the past that was obsessed with bloodworms... it's because they are conditioned to the food their breeder gave them). Of course it is best if you can convince your fish to eat a variety of foods, but I only had luck with that some of the time. Since this fish would probably do best in your tank out of all the ones mentioned, I encourage you to give it another chance.