How much weight should I move up after each workout?

[Cicero]

So when should I move up a weight for working out the biceps and triceps? How much weight should I move up? How big would the biceps be when someone can lift 45 lb dumbbells? (generally how big, the average) How big would the triceps be when reaching 30 lb. dumbbells? Im feeling very discouraged, what can I do to encourage myself to workout more?

[Wakesetter03]

Ok, First of all, you don't start moving up after each workout.
The idea is to pick a weight, say 17 pounds for beginners and 20+ (This is for dumbell exercises) if you've been doing it for a while and do that for a week, maybe two. When you feel the weights getting too light, you add weight.
45 pounds can either be impressive or unimpressive depending how you lift the weights.
45 on dumbells would be pretty good IMO, but benching? Pretty pathetic.
30 lb is pretty good too.
The way a muscle developes due to weight has a lot of factors, protein, what exercises are being done, and how often they are worked and how (sets, groups etc).

I find that I am happy to work out with a little bit of music, I always am happy to work out (that cleansed exhausted feeling after a workout is the best) but music helps me work through it.

Good luck.

[Blackout]

I increase my weights everytime i can complete 3 sets of however many reps im doing with minimal struggling. I know that I'm at the right weight if I have to struggle (not strain) to finish the last reps of all of my set, and sometimes am unable to finish my 3rd. Since biceps and triceps are pretty small muscles, you should only try to move up 2.5-5lbs at a time, especially if you are doing your exercises separately for each hand. And people's muscle sizes vary so much that its almost impossible to predict what it will be. Just take it easy and let those results come =).

[KidImage]

Bad thing about stacking up tht quick is stretch marks, happened to me but Idc.

[Wakesetter03]

Ok, spoke to my PT today:
You should have two weights to mix up.
A low one (about 8kg) for 4 reps of say 8-12, then a higher one of 10kg for 2-3 reps of 8-12. This is to mix muscle memory up.
You should be starting to fail (aka, you can't move your arm with the dumbell or the bar for benching) in the fourth rep. When you can go through the fourth rep, either add weight or reps, weight is obviously the better way to gain muscle but adding reps helps too.
I use an app for iPad called iMuscle and it is great for showing what exercises for what muscles too work out. The information on reps as well as invaluable.
I hope that explains it a little more than my first post.
Good luck!