I'm getting a new ball soon and I have a few questions about finger tip.

How many different finger tip grips are there? Is it only power lifts and ovals? What is better to use if you want more hook? What type of material should I get? Plastic or rubber?

What is the proper way to hold a finger tip bowling ball? When I inset my two middle fingers and thumb, where do I place my index and pinky finger? away or close to the closest finger?

What do most people use?

Here is a link to an article by Ron Clifton on finger adjustments called Finger Dancing:

http://www.bowl4fun.com/ron/tip11.htm

When you get to that link, at the top of the page is another link to the rest of his bowling tips articles which you may find interesting.

And I agree with Bigz on what he said about the finger grips or finger inserts.  It is all about comfort.  Some prefer inserts that are soft for more grip and some prefer hard for less grip, quicker release.  Some prefer oval, others round, etc.  Many proshops used to have samples available for you to place your fingers into to get an idea of how they feel.  I am not sure if that is still available at most proshops but you can ask at yours.  Also, some bowlers do not use finger inserts at all.  Again, it is a preference thing.