Advice: only had a fish tank for 5 months but i've learnt:
Water changes are the most important thing. I do 33% water changes per week, just to be safe on water quality.
When you check your water parameters with test kits, test your tap water if used, It surprised me how much ammonia and nitrates and phosphates were in there to begin with.
There is tons of free information on the internet just check and check again. Join a web community, there are lots of experienced people out there happy to help you, just for the love of the hobby.