Use this Study Matrix tool to help you fight the vagueness in your mind about what to do first. 

In the A box write all the topics that you're unfamiliar with ( The ones you'll want to focus first).

In the B box write down the topics you know but that do need revision.

In the C box write the topics that you know pretty well.

You can use the D box for random notes ( Tips, exams etc.)

Create a distraction page when you study. 

Use this to write down distractions as they come, even when you are working.

Whatever is on your mind, just pluck it out, write it out and store it away. 

Then get back to this page on your breaks.