Yea, it's definitely harder to overcome the nervousness on the general GRE than the PGRE because you can't skip around and do the easier/familiar ones first to get comfortable.
But I don't think it's as much a problem as it sounds...
The math section is so easy, and you have 45 minutes to do 28 problems (I think), many of which take less than 10 seconds to do in your head. So my advice here is to take as much time as you need need in the beginning to ease into the exam. Work as slowly as you need on the early problems. You'll soon get into a rhythm and probably still end up with over 10 free minutes left over at the end. That's what I did.
The verbal section is way harder, (even for non-science majors), and the time limit is brutal, considering the time it takes to read the passages. However, all of the other non-reading comp types of questions, especially the antonyms, can be moved through quite quickly because they're essentially "hit or miss". You either know the vocab words or you don't. In either case, it won't take long to pick the right answer or do some eliminations and guess. Thus they don't take much strenuous thinking like the PGRE and any tough QGRE problems, so your nervousness won't slow you down significantly in the verbal. Only in the reading sections did my nervousness slow me down, but you usually don't get passages until you're deep into the exam, so you might be comfortable by then.
thanks dear for your information.