Here's my beef with weights:
It drives me crazy when I watch a work out
video and see the instructors using 5 lb weights. I know they did not
get ripped using 5 lb weights! And then they do 5 reps and expect us to
"feel the burn"!
If you weight train on a regular basis and have been
using 5 lb weights for more than a month...put them down and say
good-bye. Unless you are doing literally 100 reps or the overhead press
routine in RIPPED, then you need to say hello to 7.5 lb weights. And
then after a month, say good-bye to those friends and say hello to 10's.
However, when increasing weights, it's easy to loose proper form. Don't! Once your form is compromised, you increase your risk of injury. Do fewer reps with a higher weight. If you want to build endurance, use your lighter weights for more reps...it will make those heavy weights seem a lot easier.
A friend once told me that she was afraid to go up in weight because she didn't want to get man arms. Rest assure, you will not get man arms, but will be toned and strong.
I use this website often: bodybuilding
If you need to check your form or the proper way to lift, there's great video clips on here.
So grab a friend, a couple of sets of weights and encourage each other to increase those weights. If you need some motivation, just click on that site...that could be you in a few months!