In reply to Up High:
Forgot to ask what grades you roughly boulder as it really depends what 'slopers' you mean - but just some general tips, they're probably obvious to you since you've been climbing for a while:
1. Explore the hold, find the best way of holding it before climbing
2. Stay low, make sure you have enough weight/body tension and that it's directly downwards (or inwards if overhang). An easy mistake to make is putting too much weight on your feet and losing contact with the sloper or your feet pushing you 'away' from the wall.
3. If it's a smooth one, usually trying to get as much contact (i.e. as much of your palm) as possible with the hold helps a lot
4. Matching slopers sometimes helps if possible
5. I am not 100% about this but it often feels to me that you mainly need forearm strength for them, maybe try training for that
6. Also resist the temptation where possible to climb too dynamically, a more static and gradual approach works best for me usually.
I'd guess that as you get back into climbing again after your break, you'll start naturally sticking them more so wouldn't worry too much yet...
Post edited at 12:08