Well, I used the Veritas
traning program the first time around. I used the "on demand" kind where you don't have the online classroom just prerecorded videos. I actually found the videos quite useless and boring, I just studied the books on their own, I found them very helpful, but that may just be the way I learn. (I think there is an option to buy just the books.)
So the first test I got a 640 and decided this process was gonna be a breeze. Studied all the books, but it seemed like my test score kept dropping, but it seemed very scattered so I wasn't very worried. I took my first GMAT and was so disappointed with my 590 after studying all summer long and school was starting up.
I then thought back to how in the world I got a higher score on my diagnostic than on my actual GMAT, and I realized that on the diagnostic I was more relaxed (no pressure to score well) and I was having fun - meaning I enjoyed the challenge of solving the problems with just the logic and knowledge I had, not test strategies from a book.
So I tried to employ that strategy into studying and execution for my next GMAT. I tried to be more curious about certain problems I was missing - used gmatclub guides and found new and different problems to study - and tried to relax more - I didn't tell any friends or family about the test to try and keep the pressure to a minimum. It worked excellent!
Let me know if you have any more questions that I can help address.