There are lots of stuffs you can do online to make money.
Apart from blogging, content writing and guest posting , there are lots of activities you can do through which you can earn money online.
Some more techniques for earning online are:
1. Design attractive logos. (If you are good at web designing)
2. Email marketing. Many Companies are offering money to promote their products through email marketing. You have to send emails related to products to the users.
More tips I will write later.