When I first started this hobby (for the second time in my life) I thought I wanted big fish. I have changed my mind so many times during this ride. There is something to be said for a shoal of smaller fish all swimming together. Not trying to talk you into or out of anything. Keep in mind that some species of fish are exceptionally social and need the company of others just like them to feel safe and secure.
Start by checking your water source to see what your water parameters are and then begin researching which fish would do well in that. Next, will you have a current in your tank or more still water? Do you like a hyper active fish or one that is more sedate? These are all things to think about.
Oh, and WELCOME to the forum! :