Hmmmmmm...how much to start out with when lifting. That's a question that comes up a lot...and it's pretty much unanswerable since everyone is different.
I'd say, if you can lift a certain weight more than 12 reps, it's time to move up. For example...if you're doing bicep curls...and you're using 5 pound dumbbells, and after 12 reps you aren't aching (going to failure)...it's time to move up to the 7.5 or 8 pound weights. And so on...
Also, just a word of advice...you shouldn't be doing the same routine three times a week - you need to give each muscle group a chance to rest. Additionally, instead of lifting the same weight each set, increase the weight and lower the reps. Kind of like a pyramid set (this is why I recommend the BFL book for beginners; it's pretty much all laid out for you). If you keep lifting the same amount of weight, your muscles will quickly become accustomed to that weight and you won't make progress. There are a lot of different weight training plans out there...but I'll use BFL as an example...the splits are set out as follows each week:
Mon: Upper body workout
Tues: Cardio
Weds: Lower Body Workout
Thurs: Cardio
Fri: Upper body workout (see, your upper bod gets three days rest - gives your muscles a chance to recoup which is when you make progress)
Sat: Cardio
Sun: Rest
Mon: Lower body workout
Tues: Cardio
Weds: Upper Body Workout
Thurs: Cardio
Fri: Lower body workout
Etc...
And like I stated before...here's how I would do those sets...
Dumbbell press - 3 sets: 12 reps@ 10#, 10 reps@ 12.5#, 8 reps@ 15#, plus a drop set of 12@ 12.5#
And so on. Can you see the pattern? in each set, you increase the weight and lower the number of reps, then in the last drop set, you DROP the weight and raise the reps.
I'm sure the other gals will chime in with their thoughts.
