1. Figure out what kind of fish you want to keep.
Look up some pictures online, create a dream board on Pinterest... Give it some time and really figure out what kind of fish you like. Different kinds of fish will require different conditions, space, and equipment. If you get all your equipment before you decide on the fish, you may end up with all the wrong things for the fish you really want.
2. Do your research.
Buy some books (on freshwater fish or on saltwater fish), join Facebook groups, forums, read blogs. You need to make sure that all the different kinds of fish you picked can live together, if not - eliminate and replace. After you have your fish picked out, learn about conditions this group of fish requires and move on to step number three.
3. Find a space for your tank.
When you picked out your fish and learned about the conditions it needs, you know approximately the size of a fish tank you will need, the bigger the tank the easier it is to take care of it by the way. Now let's find a space for it in your home. Try to find a location that will provide you with the best view of your aquarium without creating any challenges or threats to the health of your fish and the quality of your tank environment. Remember to allocate some space for accessories and account for space between the fish tank and the wall for filters, tubing, and cords. When it's all set in done you should know exactly the size and shape you are looking for when you shop for your aquarium.
4. How much do you want to spend?
If this is your first fish tank, how much can you afford to spend on a new hobby that you are not sure that you will be pursuing long term? Honestly answer this question and move on to the next step with this number in mind.
5. Price your equipment.
Shop online or go to your local pet store. You need the tank, stand, top/cover, filter, heater, gravel, decorations. You might also want to add air pump, bucket(s), chemicals, chiller, gravel vacuum, lights, siphon, timers, water pump. Luckily many modern aquariums come set up as all-in-one unites, so you don't have to buy all these components individually. Oh, and don't forget the fish and fish food :)
6. Evaluate: wants vs cans.
How does your budget compare to the cost of the equipment you will need? Can you afford a tank that is big enough for your fish? Will it fit in the space available in your home? You should address all three of these questions and then decide if you can spend more, find another location in your home or change your fish selection to accommodate your budget.
7. Go shopping.
Now when you have done all the research and reevaluated your fish selection, space limitations, and budget, you are ready to purchase your equipment. You are so much better prepared than when you started on this journey. Make sure you get all the right things and double check your measurements. Keep in mind if you need to special order anything, do so early, as it may take some time. When it's all ordered, sit back and wait for your special delivery.
8. Unpack and setup your tank.
When your purchases arrive, make sure to check for damages before you sent the mail man on his way. There is nothing worse than discovering a crack in your brand new fish tank after you spent hours setting it up. Then open all the boxes, clean it all off and get ready to go. Fill your fish tank with water once all of your equipment is set up, and let it settle for a day or so so you can make sure that everything is working properly and that nothing leaks. All this should take you a couple hours.
9. Select starter fish.
During the first day or so, while you are waiting for your tank to settle, go back to your list of fish and select a few starter fish. These fish should be inexpensive, relatively small, and something you want to keep in your fish tank in the long run. Select 1" of fish per 10 gallons of water. This time (and only this time) you can use the size the fish are when you get them to determine their impact because your fish will not grow significantly in the next 6-8 weeks that will take your fish tank to cycle.
10. Cycle your fish tank.
Now when the starter fish is in and your tank is running you have to go through 6-8 week cycling phase. During this time be very diligent with fish tank maintenance, don't over feed, watch your fish's behavior closely, do extra water changes if necessary, and don't add any more fish. Until your fish tank has finished cycling, you should only stick with your few select starter fish.
11. Bonus - Maintain you aquarium.
After the fish tank has finished cycling you are done with the setup and you are stepping in the maintenance mode. Make sure to feed and observe your fish daily. Check your filters at least twice a week. Perform a 10-15% water change every week, and scrub for algae at the same time. Every month, check all hoses, fittings, clamps, cords, lights and other miscellaneous equipment. This may sound like a lot, but a couple of minutes a day could save you from disaster months later. It only takes about 30 minutes to do a water change, including checking all equipment and scrubbing for algae. Most people find their aquariums to take under 2 minutes a day to keep everything in good order.
Now you are ready to dive into the exciting world of fish keeping! Whether you just want to keep goldfish, or if you want to delve into the world of exotic tropical reefs, these actionalble steps will get you started on the right foot.