As a very rough rule of thumb, if you're maxing out at 1-5 reps, that's training pure power and neural adaptation. If you're in the 15-20 range, you're training pure endurance (which can sometimes be a good thing, for example if you're rehabbing/prehabbing stabilizing muscles, like the ones in the rotator cuff, or your back, or if you want to perfect your form on a tricky exercise).
8-12 reps is usually suggested as a good default range to aim for with most things, where you'll definitely get strength improvements and some muscle growth (depending on how easily your body builds muscle).
I can do Standing Dumbbell Shoulder Press and Dumbbell Squats in sets of 12 reps with my current weights (3.5 lbs), but that's pushing me to almost failure.
Yeah, I'd suggest that if you're failing at 12, it's probably time to try raising the weight.
Is it okay to move up to a heavier weight if I'll only be able to do like 5 or so reps with it to start?
If you don't have an intermediate weight (where you could, say, get 8 reps before failing), one option is "drop sets", which I resort to quite a lot. So, you do a set with your heavier weight, even if you only get 5 reps. Then you drop to the lighter weight, and do two more sets of 12. So you're hitting both ranges.
Re: \o/ Welcome newbie! *g*
It depends on the exercise and your goals.
As a very rough rule of thumb, if you're maxing out at 1-5 reps, that's training pure power and neural adaptation. If you're in the 15-20 range, you're training pure endurance (which can sometimes be a good thing, for example if you're rehabbing/prehabbing stabilizing muscles, like the ones in the rotator cuff, or your back, or if you want to perfect your form on a tricky exercise).
8-12 reps is usually suggested as a good default range to aim for with most things, where you'll definitely get strength improvements and some muscle growth (depending on how easily your body builds muscle).
I can do Standing Dumbbell Shoulder Press and Dumbbell Squats in sets of 12 reps with my current weights (3.5 lbs), but that's pushing me to almost failure.
Yeah, I'd suggest that if you're failing at 12, it's probably time to try raising the weight.
Is it okay to move up to a heavier weight if I'll only be able to do like 5 or so reps with it to start?
If you don't have an intermediate weight (where you could, say, get 8 reps before failing), one option is "drop sets", which I resort to quite a lot. So, you do a set with your heavier weight, even if you only get 5 reps. Then you drop to the lighter weight, and do two more sets of 12. So you're hitting both ranges.