I swear by lateral raises! These are the most important exercise in my Delt workout. As you can see in this video I can do an entire workout with just this one exercise and the platitude of different ways you can perform them.
Play around with weight, with reps, with drop sets and supersets. Bring your arms out to the front more (for front delts). To the side (for mid delt) – which I do mostly in this video as I am obsessed with getting cartoon “Boulder Shoulders!” Or to the rear (for rear delt). Feel how your shoulder muscle reacts and watch them engage in the mirror, this will help you understand your body better and what works and doesn’t for you.