I know just how you feel! I started fumbling around in the dark with regards designing almost a year ago and I knew absolutely nothing! I continue to learn something new each and everyday!
What I did is checked out a few stores and guaged for myself how many elements, papers etc. the kits have in general. I noticed some are larger than others.
Personally, I think a good selection of elements in a kit is always nice. I don't have a set thought process when designing - but hey, I'm still only learning!
All I can say is have fun designing! I absolutely love it and have finally found my little creative 'niche' - I only wish I had discovered this sooner!