Advice/tips for a possible first time owner?

So I have a 55 gallon long tank, I owned a goldfish for 6 years but unfortunately he passed away. I've been considering maybe getting an axolotl, but I would love to know all the best advice for them, I currently have sand in my tank, should I leave it, or get rid of it? Also what filters are the best (that won't break the bank) all advice is greatly appreciated