In addition to above...

Make sure your nock point is correct. Too low, and the arrow will bounce off the rest.

Make sure you are using arrows the correct spine. Arrows that are too stiff will typically slam the nock into the bow. If you get a loud CLICK when you shoot, that's almost always a solid clue to over-spine condition.

Adjust your brace height. If the brace height is too low, it will give the same reaction as an overly stiff spined arrow. I like the method used by Fred Asbell. Untwist the string to lower the brace height until you get noise and bad arrow flight. Then twist the string up to raise the brace, a few twists at a time. Keep going up until arrow flight straightens out and the noise goes away.

About brace height. Your bow will give it's best performance with the brace height as low as you can go and get clean arrow flight and silent launch. That's why it pays to fine tune it to your shooting style and arrow selection. Note, if you are using a flemish string, be careful when lowering brace height not to untwist enough to weaken the twists at the ends of the string. Twisting is the only thing keeping flemish strings together.

I prefer flemish strings. They are almost always quieter than endless loop strings.

If your bow is newer and capable of using any of today's super string material, then use it. B-50 dacron is less expensive, but it's usually noticeably louder and gives poorer performance than the fast-flyte type materials.