Okay. Real talk. I know a lot of ladies out there are afraid to use free weights, especially the heavy ones. For whatever reason, it's a widespread notion that to be toned and lean, you need to do crazy amounts of cardio, and IF you do weights (that's a big if), do lots of reps with really light weights.
Gals, that's just straight up not true. For the majority of women, it is completely impossible to [naturally] get huge. I've been lifting for years and I actually try pretty hard (with my dietary intake) to gain more muscle. It's just not in our genes to get big like it is for men.
Also, notice that flexed, my arms look pretty muscular. BUT unflexed, they look little and toned.
Here's what I do: For almost all of my workouts, I lift to failure at 8-12 reps. That means, I lift heavy enough that I just can't do anymore than 12 reps in one set. That rep range helps to build muscle -- lean muscle.
And you must know that the more muscle you have, the more calories your body burns when you're not working out. If you just do cardio, you'll lose some of that precious, calorie-burning muscle magic.
If you need help knowing what to do at the gym, you can find tons of workouts online. Jamie Eason's LiveFit program on Bodybuilding.com is a great one to start out with.
Give it a try, and let me know what you think.