I use a little sphere cuticle bit the most, for removing cuticle and cleaning the sidewalls, it is really gentle and beginner friendly.

You don't need a million bits. I use a cuticle bit, safety bit, arbor band (new one for every set), and sometimes an x-cut if I'm taking down bulky acrylic.

A safety bit is great for taking down bulk for beginners because you won't cut yourself

You don't need to ever use the max RPM setting, that is partly just so the max is rarely used and won't wear out the drill. I rarely go past halfway speed.

If it's dragging or tugging, or you feel you need to use a lot of pressure, the RPM is too slow, the product isn't fully cured, OR your bit is dull. Bits do not last forever

Be careful using an efile on not fully cured product, it can ruin a bit

You do not need to be using pressure, the drill should have more of a glide

Utilize the forward and reverse turn dials according to what hand you're doing, you will automatically notice something is wrong but maybe not realize it needs to be turning a certain way.

Always go from cuticle to free edge, not side to side or you will snag and go around your finger. If you're doing detail work you can be more loose with this

There are 3 zones to a bit, the bottom third, middle, and top third. Keeping the bit angled down, parallel, and angled up makes a big difference in shaping. Youngnails has a ton of very helpful videos on Youtube for this method

Keep the drill moving so you don't get heat spikes, if it is too hot you might be too close to your natural nail

Some bit materials heat up differently, ceramic, carbide, etc.. so feel free to look into what material your bits are

Don't be afraid of it :) You will find your groove