JCMcHammy - sound advice you got. I boulder for fun and I feel my level (v4-v6) doesn't warrant fingerboard training (yet), I'm more interested in improving general capacity and skill before advancing to specific fingertraining. I'm much better on slabs and than overhang, so one step at a time
devnull - yeah slopers can be challenging. One tip I got was to close the fingers together, even squeeze the thumb on the index finger, as that give a stronger grip on a sloper. I used to spread my fingers to maximize surface hold on the slopers but that made the hold weaker so I slipped off frequently. But as JCMcHammy says, be precise with your body position and using the back muscles to hold on to a sloper is a better tip, you won't burn out your arms/wrist so much.