A good way is come up with a lot of topics on places you've already been to. Readers usually like to know about varied aspects of a place, and if you cover them in different blog posts, it'll keep you busy and readers happy and updated. :)
You can even blog about places in your own city which may be of interest to travellers-food, places of interest, hidden gems, experiences, weekend getaways etc.
If maybe you have travelled in past, then you could write a blog related to that place. You can also earn credits by referring tripoto to your friends and answering questions on "Ask the community "