Quick one...
1)Make sure you have enough fast growing plants such as Hornworts, Cabomba, Anacharis that will suck away the nutrients. Algae will grow when there are much nutrients(fish waste, fertilizer) in the tank.
2)Change your tank water once a week (with at least 50% water change) and maintain your tank clean from debris/waste.
3)Don't overcrowd your tank nor overfeed your fish.
4)Cut down on the number of hours of light if there is too much algae.
Slight algae will be fine.
5)Keep some fish that will eat algae after 1-2 mths of starting up an aquarium. At the beginning you won't have any algae for them to eat. So, don't buy them when you tank is still new.
Get a group of Panda Loaches (minimum 6) or other algae eaters to eat the algae.