If you're a beginner, the bigger and wider the tank, the more forgiving it is.
_Tanks:_For choosing your tank, you need to figure out how much space your fish need and how much space you have. You also should choose one big enough to accommodate the tank design you want to do. If you want really tall plants, for example, tall/vertical tanks look like good options, but they can also be a pain. If you're a beginner, the bigger and wider the tank, the more forgiving it is. There are also pros and cons to the tank material (glass vs. acrylic). You then have to consider where you'll get your tank. Pet stores are great, but they can be expensive. But if you get a used tank from Craigslist, Facebook Marketplace, etc, there are extra steps like making sure it holds water and is safe for your fish.