Welcome.
A lot of people on here recommend a dark substrate whether sand or gravel as it seems to make the fish less stressed......they also recommend sand and not gravel for Corys......you may not know what Corys are yet but you will as they’re just about the cutest most amusing fish around.....but they need to kept in groups of 6+ for their own peace of mind.......and in soft-medium water, not liquid rock like the stuff from my taps....see how it all connects? No? You will don’t worry.
This lot on here will look after you and your fish. Remember no one on here is trying to sell you anything unlike the people in your local fish store (LFS). So treat everything a salesperson tells you with scepticism and check it elsewhere. That’s rule 1.
Rule 2 is know you’re parameters: water hardness, water PH, water KH, tank capacity, tank length etc. Your water suppliers website should have the water details. You need them before you can decide which fish can live their best lives under your care.
Rule 2 is understand the tank cycling process. Fish in? Fish out? Silent cycling? Most on here don’t recommend fish in for obvious reasons. Id recommend silent cycling as it’s simple, it must be even I can do it. Most seem to do fish out cycling though it seems far too much like hard work in comparison with silent to me.
Once you know rule 2 you can start selecting which fish you’re going to keep. THATS the best pre occupied tank part.
The best science led website for researching which fish you may want to keep seems to be seriouslyfish.com. If it had been around 25yrs ago I don’t think I’d have dropped out of fishkeeping for so long.
Simply enter a fish you like the look of into SFs search bar then click on it when it appears. Most of the info needed to decide if it suits you and your tank size, water parameters, tank mates, water temp etc will appear.
Once you’ve figured out a tank mate combi you like the look of then ask about em on here as not all fish get along with others. They’re good here. They’ll see you right.
Breakfast is served...see you around. Oh and have fun doing all the above.