Remember to also work your rotator cuff muscles.
Lots of work on the deltoids without also strengthening your rotator cuff can result in impingement syndrome. Big strong deltoids will tend to pull your humerus up into the socket of your scapula and squish some important tendons if your rotators are weak. The rotator cuff muscles are designed to (amongst other things) maintain a vital space within your shoulder joint and they can only do this if they are nice and strong.
For lateral raises, personally, I would perhaps reduce the weight but improve the form when doing exercises like lateral raises. Back nice and straight with neutral spine, lift under control leading with the little finger-side of the hand slightly and then lower only as far as you feel the resistance come off, then raise again. Huge dumbells look impressive but bad technique can lead to injuries (been there, got the T-shirt etc.).
seeya
Graham
Manchester, UK