Welcome to AA!
+1 for the fishless cycle. It's less work and less stress.
Overfilter your tank. Manufacturers overrate their filters, so get a filter that's rated for a 20-30g tank.
Don't get goldfish, any type of shark, kissing gourami, silver dollar, oscar, pirahna, or pacu. They get much too large for a 10g. I'm not sure I can take another thread that starts with something like "I have 7 bala sharks, 3 oscars, and a pacu in my 20g. What else can I add?"
Tell us more about your plans for the tank. We can help you pick fish that are suited for your tank and for one another.