In nature the water volumes are usually much higher than in a home aquarium, so temperatures don't fluctuate as quickly. You'll probably find that the number and variety of fish you would like to put in your tank is higher than what your tank will actually support (Or at least, this was true for me). I've used this aquarium stocking calculator in the past and it's worked pretty well:
http://www.aqadvisor.com/AqAdvisor.p...engthUnit=inch
As beginner I also found the Youtube channels "Girk Talks Fish," and Aquarium Coop to be helpful.