I'll go first. N00bs, here are some common problems that you shouldn't worry about.
- The imfamous "brown algae bloom." It happens to everyone who sets up a tank. So don't panic.
- The nytrogen cycle. Learn it before setting a tank up. It goes Decaying matter = Ammonia = Nitrite = Nitrate = Nitrogen gas. Wait it out. Don't add anything until Ammonia, nitrite, and most of nitrates are gone.
- Feeding. Don't feed your fish every day. Nano tanks build up waste easily, so feed every other day or every three days.