Hi there! Here are my thoughts on your questions.
How many background pages is a good number to start with for a kit?
This varies from designer to designer. I know designers who offer as few as 6 and others that go as high as 20. I tend to do 8-12 depending on the kit. Always go for quality over quantity.
How many elements?
This varies even more than the backgrounds. anywhere from 12-40 is the 'norm' although I've seen kits with much more.
What are the elements you consider essential to have in a kit?
I wouldn't say that there any essential elements, but rather catagories that should be included in a kit. You want to make sure you have some from each of the following catagories (note this is not an exhaustive list of the possibilities, but you want to make sure you have something from each area)
Long, trim like elements - examples; ribbons, ricrac, strings of beads, borders, stitching
Fasteners - examples; photo anchors, photo corners, brads, staples, eyelets, tape, binder clips, paper clips
Tags/Journaling elements - examples; tags of all shapes, index tabs, journaling strips, mats
Embellishments - examples; buttons, flowers, word elements, doodles, etc.
How did you first start to offer your kits? Blogs? Freebies forums?
I put one kit in the free downloads section here at SBB. After that I started selling them. I still offer freebies on my blog.
How much do paper scrapbook trends influence your digiscrap designs?
Hmmm, tough one. I don't paper scrap or read paper scrapping magazine, so I have to say not much. Of course paper trends influence digital in general so, I'm sure I've been indirectly influenced. Still I think paper scrapping is being affected by digital scrapping too, especially when it comes to title/font work and photo manipulation. Don't be afraid to try to set your own trends.
What's the number one tip you have for a new designer?
Well, if my new designer, you mean you are interested in selling commericially I would have two pieces of advice. One, you must absolutely love it. Those who last in the business do it because they love it. The second one is, to make any money you need to realize it takes both having a unique, quality product and being willing to put time in to promote yourself and your work. There are many very talented designers who sell very little because they don't promote themselves. With the number of designers out there - you have to do something to stand out. Of course if you are not interested in selling, you don't have to worry about any of that. The great thing about designing is you can make exactly what you want to go with your photos
I wish you all the best in your design endeavors and look forward to seeing your work! Have fun.