How to stick within rep range

Hi,

This isn't the normal how many reps is best for bodybuilding question but more a question of once you have decided how many reps you are going to do, how do you keep around that rep range per exercise.

For example, say I decide to stick with reps of around 8 per set, on my first set if I chose a weight that I can just about do 8 reps with without going to failure, by the second set I won't be able to get 8 out and if I stuck with the same weight by the time I get 3rd/4th set I would probably only be able to push 3/4 reps out.

If I chose a weight where I know I'll be able to get 8 reps out on say the 4th set, then I won't really be pushing myself as much on the first 3 so would these be wasted sets?

The only other way of doing it would be to decrease the weight after each set I suppose.

Just wondered what other people do?

Cheers,
Dan

There are different ways of dong it m8.
 
If say doing 3x8 pick a weight (same weight for all sets) you could do say 14-15 reps but stop at 8 on the first set, same weight you could do say 12 reps on 2nd set but stop at 8 and on the final 3rd set you stop at 8 and 9 would of been failure. This is the proper way to do 3x8.
 
However I prefer 3x6-12. Pick a weight where you can do at least 3x6 same weight with all sets and each week try to increase the number of reps you can do per set, when you can do 3 sets of 12 up the weight, I find this easier to make progression but either way is ok to use.  
 
Edit - And always use the same amount of rest between sets (what ever that may be) otherwise if this is a variable how will you know if you have made progression when doing extra reps if you might of had rested longer. 

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