As long as you're careful, it's nothing to be super scared of!
I use normal, human nail clippers. Though some people are the opposite; I personally think it's harder to make a mistake with them, and I'm more comfortable with them.
If your piggy has light colored nails, you'll be able to see (or faintly see) the pink, flesh colored quicks. As long as you don't cut them, or cut right against the tip of them, the nail clip won't hurt your piggy at all. As a precaution you can always trim the nail a little less than you think you should; or trim just the nails' very tips your first time.
With each nail trim, the quicks will begin to recede, making it easier once you start regularly trimming her nails. Most people do their piggies nails once a month, but if her nails are very overgrown now, you could probably trim a tiny bit off once a week until they're normal length.
We just have one person hold the piggy normally (usually with a treat ) while a second person trims. bpatters' link is really fantastic, and everyone helped me so much with nail trim advice here, too:
https://www.guineapigcages.com/foru...ail-trim-phobia-please!?p=1013202#post1013202