There are a lot of ways to generate income with your blogs.

1.- Donations: You can add a paypal button or a bitcoin address to let people send you donations.

2.- Ads: You could add ads to your sites to win by each click you get on them:

3.- Urls shortener: With services like Adfly you can earn for each click you get on a url.

4.- Referrals: You can add referral links to sites who offer this service like casinos or exchanges.