I would go to the store and see what fish are available and are appealing to you. Make a list and then run the list by some of the folks here at Fishlore to see what would be compatible with what you already have.
You don't have your location but some of the fish farms allow you to pick up at their facility.
You want to choose at least 2 schooling fish. 1 that will swim mostly upper middle like harlequin Rasbora and lower middle like neon Terra's. Albino cories or some higher temp cories for the lower level. The Dwarf Gourami will swim all levels. So will swordtail fish or platies.