This was some advice that worked really well for me. Read one paper per day. Print it out, read it entirely (edit- or skim the relevant sections), and make handwritten notes at the top of the paper that will summarize the one-sentence importance of the paper and how it may apply to your research. You will slowly build a database in your head for when you start writing.

Plus, one paper a day is manageable and a realistic goal and helps you build confidence in your topic.

edit- To the people saying this isn't reasonable: that's fine, each field is different. This post is about setting tangible goals. Find a goal that works for you and stick with it. Create a program and stick to it. IMHO this sub needs more contributions on how to be successful in grad school and where to start.