Came across a problem when I started working out.  I am shooting to add mass so I am sticking to a 3 set per workout program.  For example, when doing DB presses, I shoot for a 10,8,6 workout.  I start off with about 30 lbs  and I am able to complete the 10 I need and sometimes even 12 reps. but when I move up to 35 I can barely complete 7 and may sometimes get lucky and do 8.  I can only get it up about 4 times with the 40 lb weights.  Is this method correct,  I am maxing my muscles out I think, I still feel sore after 5 days of working my chest.  I contribute this to the fact that I have'nt been in the gym for a few months and may have strained the muscles lifting heavy the first time.

Why are you trying to lift so high a percentage of your max weight so early?  If you just started you should be spending AT LEAST 2-3 weeks doing moderate (no more than 50% or so or your max) weight and nail your form down. By this I mean get a really good feel for how your muscles feel when doing each exercise correctly. It sounds like you're setting yourself up for one of the classic beginner mistakes, doing too much weight too early and getting too sore and risking a) injury or b) quitting because lifting is 'too hard'

RELAX, slow down, you've got the rest of your life to go heavy, DON'T think that you can 'cheat' the process by lifting heavy immediately. I wouldn't concentrate on 'mass' versus 'strength' until you have at least gotten a solid month (maybe even 2) of working out all muscles groups with the intent to get a feel for how your body feels when doing the exercises.

Paul