I have a 150 gal tank. I use glass pebbles on the bottom. It's very easy to vacuum clean and the fish love foraging it in. There's no rough edges to scratch them either.
I have 2 whisper top filters and 2 canister filters, 2 air pumps running with bubble wall stones. I use the API master test kit, test strips do NOT work! I also use the API Quick Start liquid for new setups, and the API Stress Coat liquid when I do any water changes.
Buy a glass tube heater made for your size tank, go larger if you have to don't buy a heater for a smaller than 60 gal tank as you'll burn it out quick!
I use Repashy Soilent Green gel fish food. Flakes have little to no nutrition. Pellets are better but if the fish swallow it before it's totally absorbed all the water it possibly can before falling apart it could swell in the fishes tummy (like birds eating uncooked rice).
Do not over feed! Fish don't have stomachs. If you over feed they can and generally will get swim bladder disease and end up either sitting on the bottom of stuck at the surface. Feeding small amounts twice a day is the best!
Don't buy fish that are in tanks with sickly or iffy looking fish, or in a tank with live plants or live snails. I don't know what kind of fish you are getting, but do your homework before adding an algae eater (pleco) as they attach to certain species of fish and literally suck the protective slime coat off the fish and the poor fish will die!
Snails are notorious for harboring diseases. They also multiply like rabbits. You may have gotten just one snail, but one morning you'll notice hundreds of little guys (hopefully before your filters clog and burn out)
If one fish looks sick, put it immediately onto a separate "hospital" tank. Do not treat or medicate your entire tank!
When setting up your tank, if you know someone with a healthy well established tank, get some of their used filter material and take it home in a container of their tank water. Add it immediately to your filter once you have water flowing through it. This will enable good bacteria to colonize much quicker. This bacteria will basically eat all the harmful chemicals your fish out out just by swimming and eating. Without a stable bacteria colony the fish will not thrive!
Do not over stock your tank with fish! If you do the bacteria colony will not be able to control the ammonia from excrement, rotting food, or what comes from the fish "breathing" process. Check how much water each fish needs to thrive and calculate how many can live safely in your tank.
Some species of fish cannot live together. Check before mixing species. Even certain types of goldfish don't thrive together!
Make sure you have safe places for the fish to hide. Everyone likes a little area to relax!
Don't put any decorations in there that a fish could get stuck in.
Never do a water change more than 50% of the tanks capacity. An established tank should only need a 20% water change weekly. Keep an eye on your ammonia levels. If they never seem to drop down to nearly zero, you've either overstocked your tank (too many fish) or are feeding them too much and rotting food is causing ammonia levels to rise.
Its always better to have more filter power than the box recommends. Get at least a filter recommended for a 75 gal tank!
Never leave the tank lights on all the time. Fish need darkness to sleep too!
If you must put your hand in the tank thoroughly wash them first and rinse them very well!
Get a thermometer for your tank. When adding or changing water, put the hose nozzle up against the thermometer and adjust the water using your taps til the temp matches what the current temp is in the tank. If you are using a bucket put the thermometer in the water in the bucket to make sure it matches tank water temp. Even throwing the tank water temp off a few degrees will shock the fish and possibly cause death.
Never use any type of soap or cleaning spats on anything associated with your tank. Even if you think you rinsed it pretty well residue could still harm your fish. The only exception to this hard and fast rule is your hands!
Get a net if you must take a fish out of the tank. Never touch your fish as this messes up their protective slime coat.
Whenever you add a fish sit the bag in the tank for at least 20 minutes before using the net to add him to your tank. This allows the fish to become gently acclimated to the new water temperature. Do not ever add the fish store water to your tank!!!
Do not set up your tank by a window. Direct sunlight will cause green algae to bloom super fast. Algae is alive and will use all the oxygen in the tank and leave your fish gasping at the surface.
If you need more questions answered, I will be more than happy to help!
I just bought a new house and had to move the tank the day before the movers came so I could focus on getting the fishies safely moved. It's not fully set up yet, but you get the idea!