The general concept is to simulate the natural lighting enviorment. Since our fish are tropical they are in an area of the globe that gets on average 12 hours of light and 12 hours of dark year round. Unlike the US where we can range from 8 hours of light to 14+ hours of light depending on the season.
Lets say you shoot for 10-12 hours of light on your tank. The second thing is that most folks want their tank to be lit in the evenings when people are home to enjoy the tanks. This often results in the tank's light cycle ending at 10-11pm and sometimes 12pm. So we then backtrack the approprate hours of exposure to when the tanks lights should come on. Since this is usually in the middle of the day a cheap on/off timmer from wal-mart or the local home improvement store. This will allow you to have a fixed time cycle with no fuss.
When battling algae its best to approach it by finding the source of the algae vs simply lowering the light exposure as you will in effect never remove the algae from the tank. Figure out why the alage is in the tank and work to remove its food sources above and beyond the light. If your tank is FOWLR
than it wont be a problem to keep the lights off for a few days and only have ambient light on the tank.