I just pick a weight that's sort of hard (usually a machine rn until I feel I can start to do free weights again) and increase it by 5 or 10 lbs at 10-15 reps. Usually end up doing about 80 reps. Is this bad? Meh? Did it on calf raises, leg curls, and leg extensions tonight. Leg press was low, like around 40 because my legs are a little 
from doing the abductor and adductor machine last night (didn't pull anything, but did get a good ahh stretch from the one that is like a goddamn spreader bar but I definitely feel it lol). Once I fix my quad dominance from biking erewhere I'll lower the reps and focus strength, but yeah what do y'all think? Also any good ways to ensure my muscles around my right knee get to a point where I don't have to worry about it potentially taking a road trip when I side step with my right foot?
if you can do more than 5 sets of 10 reps, you're not doing enough weight. if you can 5x10 a weight, next time add 5-10lbs. aim for 8-10 reps per set. try to get onto free weights soon, it's just overall better for your muscles to fight gravity directly. do a good 5-10 minute warmup before every leg workout. i do a series of yoga poses to warm up my back and legs. i just finished up a "squat every workout" year and noticed the biggest leg gains of my life, and i've been doing this for 18 years