dont know what you're doing now but, you could try a bunch of things.
1. go heavier
2. rest more between shoulder days.
3. dedicate a day to shoulders, train them independant of other body parts, never before a heavy chest or back day and never the day after.
4. work on your biceps a bit more, this aids in shoulder developement and creating an illusion of nicely defined side delts, especially the hammer curls. Contrary to popular belief, the biceps are the fastest recovering bodypart, not abs. you can work them a bit more.
5. throw rear delts in with your back day, the most underdeveloped part of the shoulder especially on women. then you really get them responding.
6. train your shoulders 2x per week, one heavy day one moderate day, it is okay to include them WITH chest for the second day.
here is an example:
M: shoulders
T: legs
W: back
T: abs/cardio
F: chest /shoulders
S: arms
S: Rest
something like that, you get the idea.
7. partial reps work great for shocking efffect once a week
8. periodization is alway a standby
Theres more but I'm starting to ramble. Shoulders are my fav, I have tons of shoulder programs...
example 2 shoulder mass builder 2 minutes rest between sets.
I'll give you the weights I use ONLY as example, you have to figure out your own.
I start with: a serious warm up, a series of 6 shoulder specific exercises with 2.5 weights, takes about 10 minutes. then: first pushing.
seated overhead BB press 5 sets including w/u of 10 bar only then 8,6,5,5
8/65lb, 6/75lbs, 5/80lbs, 5/80lbs
then to a pulling exercise
upright rows
same sets and reps
45lbs 55lbs 65lbs 65lbs
reverse flys (only machine I ever use for shoulders)
50,60,65, 70lbs
front lateral raises
12.5, 15, 20, 22.5lbs
side lateral raises
10,12.5,15, 17.5
this is only an example....
11. eat more
12. rest more for growth...
I change my shoulder program EVERY week. I vary reps, sets but keep the days consistent. and keep the weights consistant for whatever goal I have at the time.
I have found for building (for me) I have to go heavy and use free weight, no machines. I do use cables a few times a month for a change. dont forget your traps and do shrugs sometimes too.... arnold presses really helped to develope my delts too.... anyway, like i said i dont know what you're doing now, I'm done rattling on... hope that helped in some way or another..!