how many reps?

bearxfoo

I'm really confused at what/how much I should be doing at the gym with the weight machines or strength training. I do mostly cardio because I'm focusing on just dropping weight right now, but I know that doing strength training can help a lot too.

But I never know how much to do. Do you HAVE to get to the point where you're sore to "see results" or what?

pisilisa

Yes, in general your muscles should be sore/worn out after you're done with your sets.
I recommend doing three sets with 10 repetitions. When you start, the weights should be so that you can't do more than 7-8 reps per set, eventually you'll manage 10. When you manage 10 repetitions in all your three sets, you should adjust the weights again so that you only manage 7-8.

Everyone should combine cardio with strength exercises!

wellbert

starting strength suggests 3x5, adding weight each week
stronglifts, 5x5 adding each week...

gmjminsz

Depends on your goals

1 - 3 reps = strength and power
4 - 6 = strength
8 - 12 = hypertrophy
12+ = endurance

Generally, beginners are fine with 3 x 10.
However, around 24 total reps is usual for one exercise, e.g.
4 x 6
5 x 5
3 x 8
2 x 12

You can also apply periodization, e.g. WK 1 = 4 x 6, WK 2 = 3 x 8, WK 3 = 2 x 12. This would give you a heavy, medium, and light weeks.

Stronglifts and starting strength are designed for exactly what they imply: strength