I'd ask you to elaborate on the bolded part, as it sounds utterly ridiculous to me, but I'm afraid it'll turn this thread into yet another leeching discussion, and Lord knows we've had plenty of those.
The best way to play is to play how you like it. If you feel you need to get to know your job some more before you get into the higher levels, then by all means, take your time, solo, try some lower level NMs or do quests/missions at your level. Otherwise just level it up, jobs and their roles change a lot at higher levels and aside from general gameplay-lessons you won't need much of what you learn at lower levels later on. And skill is a lot faster to gain at higher levels as well, so shouldn't worry about that too much. As I said, just play how you feel like.