Here are some basic rep schemes you can use based on your training goals…

Hypertrophy

10×3 at 85-90 % of 1rm
5×5 at 75-85 % of 1rm
10×10 at 60 % of 1rm

Maximal Strength

Work up to your 1 rep max, and then do 3-4×3 of 90-95% of that 1rm
Pick a percentage to rep out at and try to set a rep record
Work up to a 3 or 5 rep max, and then take 80% and try to get it for 10 reps

Dynamic Effort

Deadlifts 8×1 at 50-70%
Bench Press 8×3 at 50-70%
Squats 8×2 at 50-70%