First things first. Arm yourself with a great pair of clippers. I think The First Years American Red Cross Deluxe Clippers are the cat's meow. The magnifying glass is a throw away, but the clippers themselves are incredibly sharp, which is a good thing. Think of it like shaving; you are far more likely to injure yourself when using a dull blade. The same holds true for clipping! Have faith, you can do this.
Once you get proper clippers and are ready to cut:
1. Wait until baby is passed out.
2. Put baby on tummy in his crib.
3. Position yourself comfortably and gently pull pad of finger away from nail.
4. Slip the bottom half of the clippers behind the nail but on top of the finger pad.
5. If you are clipping fingernails, cut at least 3x per nail creating a rounded edge: once on the right side, the next on the left side (creating a point for the tip and avoiding sharp corners when the nail grows out a little.), then the last clip should be cutting off the point.
5a. If you are clipping toenails, clip flat across the nail so you avoid ingrowns. It can happen, take my word on that!
Here is a crappy youtube tutorial I made:
If you DO nick baby:
-Run the finger under cool water.
-Apply pressure with a tissue or cloth until it clots.
-Do not put on a bandaid!
-Remind yourself that this is much harder on you than it is on baby.
-Give baby lots of cuddles until you feel better.