Contribute to the forum and eventually, once your forum rank is high enough, you can participate in a signature campaign assuming you are a quality poster and have positive trust at that point. There are faucets and this sort of thing but IMO they are a waste of time as you will literally only make a dollar in one full day of work. If you really want to earn a good amount of bitcoin you're pretty much going to have to invest. Maybe give freebitco.in faucet a chance and get lucky enough to roll 9999 and get some bitcents going for you. Nothing in life comes free or easy my friend