Dude, someone just asked Dave Henry a delt question, in the current issue of MD, that I picked up a tip myself. I'll give you a couple other ideas that are sure to work as well so I do apologize for the length of my response. I personally gave this a try just the other day and got some burn and pump I haven't had in my medial (side) delt in a long time. You're going to use three sets of dumbbells, start about 10lbs lighter than what you normally do for your 6-10 reps. Lets use 15lbs for example then grab some 20's and some 25's. Then you're going to run up the rack doing 5 reps for each weight. Looks like: 15x5, 20x5, 25x5..this will be one set. You can either do three sets with the same weights or you can move up 2 to 5 lbs for each dumbbell for each set. Looks like:
15x5 20x5 25x5
20x5 25x5 30x5
Now I read another variation to this you can try where you start higher and DROP in weight every 5 reps. Either way, you are going to have some serious blood flowin' and if your diet is in order, you should notice some results pretty quick. If your mid and rear are whats lacking and you're happy with the front portion of the delt, I wouldn't recommend anything but either one pressing movement or front raises for 3 or 4 sets. Whichever you decided to go with, save the front for you last excercise and use "maintence" weight. Now the rear delt excercise I recommend is a bit tricky to describe. BUT IT WORKS! Rear delts are very often forgotten by a lot of people and it really can throw off a well developed back. Remember to, that the rear delt is a very small muscle and you can't do "macho" weight with it....at least with this excercise. Let me try to give you a mental picture first for the setup. If you were standing straight, hold your arm straight out to your side with a closed fist as if you're gripping a dumbell, now put a slight bend in the elbow, in an arking movement bring your arm across the front of your body until it is inline with the opposite side of your chest or delt. Now do all this lying on your side on an incline bench (i find a decline bench works best while I drape my non working arm over the leg braces) Ok now do what I explained a moment ago with say a 5lb DB. I know that light sounds crazy but for starting off and to get correct form you need to start light until you get the hang of it. So, you're lying slanted now and with your right arm(working arm) hangin down, slight bend in the elbow, pull in a straight line with the rear delt (pretty much with the DB passing just under your ear)LEAD FROM THE ELBOW, until your arm is just past vertical so you get a good squeeze in the rear delt (once you reach the top(contracted) position, you could supinate(palm up) your wrist just slighty to really squeeze the muscle for peak contraction). Then lower the dumbbell back down keeping tension on the delt and slow and controlled. OK OK, I know that sounds VERY confusing and it is difficult to explain. I looked for an illustration online but nothing....if you can make to Barnes and Noble or something...or if you have it already, Arnolds Encyclopedia of Modern Bodybuilding has a picture or two of Arnold doing this. That's where I got it and it works wonders man. It is VITAL to really focus and form that mind/muscle connection to really feel that small muscle working. Like I said, start light and work up...I leave with a nice pump in the rear head every time and this is the only excercise I do for rear delt. Sorry if I made this confusing.....if you have any questions let me know and I'll try to come up with a better way to describe it. I do think you'd see some great results if you lay off the front and really hit the side and rear with some high intensity and more weight. Take it easy bro.