GMAT club has plenty of resources for studying, practicing and discussing test & question strategies. What I like the most:
1) Review of prep materials - pros & cons, the free resources, free practice tests
2) Discussions/approaches to solve OG questions - when the OG explanation is just not good enough
3) Quantitative handbook - free, excellent, concise
4) AWA section - memorized the template the night before the GMAT and it was perfect
5) Quizzes - the BEST RESOURCE. The quizzes and question pool available are perfect for testing yourself with unusual/stressful questions. They may not reflect the actual GMAT completely, but its really useful to go through them (and the explanations). The analysis tool lets you understand your strengths & weaknesses very well.
Don't take the GMAT without referencing GMAT club.
Learning to skip tough questions is the hardest skill to master in the GMAT. Good luck