How do I increase my ability to understand complex reading comprehension for the GRE?

Answer 1

There are really only two answers to this question, and they're both tedious (apologies ahead of time).

The first is the most obvious and least helpful, but it's true nonetheless—read! A lot! Find something you're interested in, find as much as you can to to read about the topic, and challenge yourself to read about it at the highest level you can. If you find yourself struggling but sorta-slowly starting to get it, then you're reading at about the appropriate level to improve your skills. Just keep practicing; it's the only way.

The other tip I have is to study vocabulary, particularly your Greek and Latin word roots. I found that to be the most productive "pure studying" I did for the GRE, and if it's like it was back then, it will definitely contain a healthy amount of classically-derived vocabulary, so Greek and Latin flash cards are a handy tool.

Hope this helps!