always tips on every finger
although there are some exceptions
Jackson SL-3 Soloist w/ licensed Floyd Rose
Peavey VK 100 Head
Earcandy Boa 2X12 Cab w/ 70 watt Speakers
Fender Frontman 15 Watt Practice Amp

I pretty much just go with whatever feels comfortable and gets good sustain. Just try to get a feel for what is right for you.
Use any part of your finger but if your not supposed to be muting a string then you should be playing with the tips. you can use your pinky to roll in sweeps so you don't always play on the tips. Limitation should be your only limitation. Use all parts of the hand if you can or want to.
The reason this is such a concern for me is because I think my current hand positioning is keeping me from playing as fast as I want to. As far as speed, my pinky is the biggest roadblock. How do you position your pinky on the fretboard when doing pentatonics, or is it the same as any other position?
Quote by led,rainsong
always tips on every finger
although there are some exceptions

This brings up a question...I've been playing for a year or so and on some stretches i sort of end up using the outside edge of my index finger. Like if I drew a straight line from the tip of my index finger to a little above where the nail detaches from the skin. It's hard to describe in words exactly...is that okay?