Welcome.
Its good that you’re researching before buying. Long term fish keepers on here will tell you they wish the internet had been around when they started off.
Lesson 1: Don’t take an aquarist shop employees advice at face value, they’re trying to sell you something. Ditto a lot of the internet.
Lesson 2: Read up on cycling your aquarium. (I prefer silent cycling as the other methods seem way too complicated for my tiny mind). Though you may understand the others easily.
Lesson 3: Find out your water hardness from your suppliers website. Keeping fish suited by millions of years of evolution to your water hardness will give them a better longer life.
Lesson 4: Don’t be afraid to ask a question on here. Everyone’s helpful and we all start somewhere.
Lesson 5: Have fun.
Seriouslyfish.com will help you discover the needs of any particular fish that takes your fancy. Water hardness, alkalinity, temp. Tank size, tank mates, plants, food, breeding etc etc. It’s science backed and not a product of hearsay, rumour and you tube nonsense. It really is the best site of its kind on the internet. Pre-internet it would’ve been a book the size of a car costing more than an aquarium and it’s contents. Use it.
Stay safe and have fun.