Best source and most profitable to me is getting a job which pays you in bitcoin. Many on this forum pays bitcoin for those who can work Computer based freelance. Its better to work on your skills and develop them.
Trading will be the best income source for bitcoin there are other option but i don't considered you to use it HYIP is the most dangerous way to grow our bitcoin if you are just using the affliate program then you can earn profit at least 10% of initial deposit. Also investment in ico's is good but does not mean you are going to invest it's always up to you if you really want too.