"What size tank should I get?"
Most people would say this is your first real decision, well, they'd be wrong. When looking to start a new aquarium your first big decision should be the type of fish you want to keep. Do you want a nice small tropical community fish tank? Or are you more interested in the bright and exotic colors of cichlids and saltwater? Once you have decided the type of fish you want to keep, then you can move on to looking for that perfect tank.
"How much space do I have to spare?"
Get the biggest tank you can. Don't put getting the tank of your dreams off until later just because you don't have a spot for it. If you don't have room enough to get the tank your fish will need at their full size, either make a spot or choose a different type of fish. There's no sense to get a fish that requires a 75 gallon tank and put it in a 20 gallon expecting to upgrade later on when it outgrows that tank. This is detrimental to the fish and in reality, unless you're a dedicated aquarist, you're not going to upgrade that tank when it's time. Get that big tank to start with, you won't regret it.
"Bigger tank, more work."
Wrong. The bigger the tank, the easier it is to maintain. That cute little ten gallon tank? It's a nightmare. Once you put fish in that tank, you're looking at an endless cycle of ammonia and nitrate spikes and water changes. The more water you have, the less you're going to have to worry about chemical spikes (so long as you stock your tank properly, and maintain your filtration). Though just because you get a bigger tank, that doesn't mean you can shirk your duties. No aquarium is safe if you don't keep an eye on your levels.
Long story short; don't base your decision on the little thinks like space or easiness.
Think about what the fish need and what you're able to provide for them.
Thank you for visiting!
True Color Aquatics