You'll have to keep in mind what type of tank you want. For example if you want a reef (coral) you'll need to invest in good lights. A sump is recommended so make sure you have a stand to fit one inside, etc. Like Smitty said the pinned posts will help, but I'm sure you'll have some specific questions. RO/DI water is recommended, best to get your own filter, but maybe you have a LFS that is close by and you can buy the water direct from them. If you haven't figured it out in your readings yet, this is expensive and addictive hobby that requires a lot of patience. Good Luck & ENJOY