/fitl/let here (before you ask, yes I read the sticky)
How do you know when you're ready to transition to a heavier weight?
I've recently started with a 20 pound weight for both arms curling inward and bent-over lifting. I'm currently doing 10 sets of 10 reps on each arm for both inward and bent-over lifting (so 400 total reps which takes about 30-40 minutes), and I've only been lifting for a few days. My right arm is significantly stronger than my left arm so only my left arm feels strain after I lift.
I should also mention that I weigh 207 pounds and I'm dieting at 1500 calories per day (mostly protein and carbs) and I've been dieting for a couple weeks now (but I've only just started lifting). I live on a large college campus and I usually get lots of cardio carrying around a backpack of books up and down steep hills and staircases all day, but I hate exercising in public so I just lift with the dumbells I have at my apartment.
So should I wait for my left arm to catch up before I move to a heavier weight? And how do I know when I should move to a heavier weight? When I stop feeling strain after I lift?
Try a bigger weight. Can you do 8-12 reps with it before failure? If so, you're ready for that weight.
If you start to do 13/14+ reps with your current weight, try doing a set with a slightly higher weight