Algae is natural and will always be present in a healthy aquarium, so it is not "bad" as such. However, there are some stubborn species what I tend to refer to as "problem algae" that can easily take over. Prevention is usually the best method and it is quite simple.
If you have live plants then you need to find the balance of light/nutrients for the plants but no further, and algae will always be disadvantaged. However, algae on the glass is still likely, as every surface under water forms a bio-film and in addition to microscopic critters and bacteria, algae will appear. I always clean the inside of the front glass (side and back glass is up to you) at every water change (once a week) even if I don't see anything (I usually don't, that's the point). I use a sponge-type scraper as this is easiest, and it will deal with the bio-film if used weekly.
Provided your tank is biologically in balance (not over-stocked, or inappropriately stocked, fish not being fed too much, regular weekly substantial partial water change, regular filter cleaning) this should be all you need to do.