I just started working out three months ago, making the first real attempt in my life to get into a serious workout routine. I've always had skinny little arms and have trouble building muscle in general. After having put in a few months, I have noticed some results; however, I'm having a lot of trouble with my front deltoids, the left one in particular. I've been doing front raises and various other shoulder exercises, but the left front delt just isn't really going anywhere. Now, I should probably emphasize that I have BONEY shoulders, and my left arm is significantly weaker than my right. I guess my real question here is if there's an effective way to train my weak shoulder that is a little more beginner-friendly. When I do front raises, I can do about ten reps with a light weight, but after that I literally can't raise my arm anymore. I'm also worried that when doing raises, my shoulder is so weak that I'm not using proper form. Any ideas?

first and foremost do complex movements not isolation movements and exactly what are you doing as far as a routine goes-what is your schedule,exercises,sets,reps,and cardio-and there are a few different things that can be done to even out imbalances but lets start with your basic routine

I devote one day a week to shoulders, on which I do four sets of side laterals (10-12 reps), front raises (10), rows (10-12), dumbell presses (10), and shrugs. I also have a day for chest and biceps where I do curls (10), bench presses (10-12), butterfly curls (15-20), and pushups (20). I have another day where I work on biceps again with additional focus on my triceps. My third day could probably use some revision. As for cardio, I go running once a week and jump rope every other day throughout the week.

Edit: Here's a more detailed breakdown of my routine of sorts. I do four sets of each.

Day 1:
Lateral raises - 10
Front raises - 10
Overhead dumbbell presses - 8-10
Rows - 10
Shrugs

Day 2:
Curls - 8-10
Bench press - 10-12
Bench butterfly curls - 15-20
Pushups - 20

Day 3: (this one could admittedly use some work)
Not sure what the name of this one is, but I lie on the bench with a dumbbell in each hand lifted straight out above me, lower each to where my hands are ear-level and back up. I do 15-20 of these.
Curls - 8-10
Pullups - 3-4
Pushups - 20

check out this thread for a full body workout for starters you should be focusing on full body workouts for at least the first year you are working out serious here is the linkhttp://training.fitness.com/weight-training/full-body-just-dumbells-26787.html
we can modify this for you if you want but this is the basic idea

If you want better result, your going to have to do MORE than once a week on your shoulder, like he mentioned, give full body workouts a go.

And concerning your technique, the plane of flexion is on the scapula. In other words when you front raise it shouldnt exactly be straight but about 15degrees towards the middle, also try and focus on just using your deltoids rather than having your arm help.

Thanks for the advice. I'll give some of those full body routines a shot. A few things though: is there a particularly good way to break those down into which days I should do certain exercises? For instance, should I work chest and biceps in one day, etc? Also, since my shoulders are my weakest point, would it be advisable to have one day focusing on shoulders and throw in a couple of additional shoulder exercises for the other two days of my workout as well?

fullbody workout does every muscle every day normaly 3x a wk m,w,f,
it could be like this
squat alternate with deadlift
bench-press
chins
millitary-press
bent-over-rows
dips
no isos needed but if you want to add them its up to you.

legs-walking lunges,squats,step ups,bulgarian split squats,deadlifts
chest-flat bench press,incline, decline, dips, fllyes
shoulders-military press(front delt emphasis,upright rows,flyes,front raises
back-bentover rows-(db single arm elbows in or out-and barbell), flyes,pullups
triceps-overhead extensions,lying extensions,kickbacks
biceps-any variation of curl
calves-heel raises standing holding db or seated with db on top of thigh
abs-crunch (with db overhead-advanced),hanging knee raises

dont do all of these just pick one per body part to start with and do 3x10-12
every other day 3x per week is best mon wed fri or tues thurs sat also you have to microperiodize by going heavy light heavy light this gives you two heavy days one week then two light days the next week this allows for proper recovery and as far as cardio goes do it right after weight training or of you dont have time do it in the morning and lift at night but not too late or you wont get no sleep-your weight training workout should be done in 45 min and your cardio a minimum of 20 min to start

---just in case you did not read this it should have answered these questions already-----------------------

if you have any questions why i chose the bodypart order just ask

these exercises can be changed from db to barbell for the most part but if you have any questions regarding this just ask and i will modify for your goals