Just be sure that you have some styptic powder. I had been clipping Sir N's toenails for years without incident. Then one day, he tried to push away from me just as I clipped. Only a few milimeters of his toenail was left. Blood shot out and hit the opposite wall. I held him practically upside down by that leg and grabbed the styptic powder and poured it on very, very liberally. Then I ran for a taxi to go to the vet's office. I was holding his leg up the entire time, trying to keep it above his heart. By the time we got to the vet's office, he had stopped bleeding. It took another couple of hours till I stopped crying.
I still clip his toenails and Little C's, too. But, before we start, I always make sure that we have that styptic pwder within easy reach. That stuff WORKS let me tell you! I shudder to think of what might have happened if I hadn't had it on hand that day.
Now, as for clipping, I've found that the easiest way for ME to do it is to sit on the floor with my legs stretched out in front of me. Then, I make them lie down on my legs, belly up, head towards my knees. With Sir N, my legs are flat on the floor, but with Little C I have to raise them up because she's so tiny. I hold their little paws VERY tightly now to try and prevent unauthorized squirming. I talk to them quietly, praising them for holding still and telling them to hold still if they try to wiggle. And, they get snuggles and treats when we are finished.