I may be wrong but I think that the XLayer itself is/was originally designed as a jerkbait. A lot of people will tell you though that it's effectiveness is massively increased if you can allow longer pauses or just tiny skips and hops in your retrieve. In strong current they can be effectively drifted at the fish with very little action required on your part. In less current, personally I like to fish them almost in a sink and draw style. I caught a lot of fish on them when I started (probably like most did), assuming that you had to keep them jumping and moving all of the way in. Since slowing things down massively though, catches have improved.
Fishing them now (on a usual mixed, mostly sand bottom) around here, I let them sink to the bottom before winding in any slack line. Then, with my rod held away from me (tip held high), I'll lift the bait with a smooth action while wiggling the tip (if that makes sense) for about 3 or 4 feet perhaps. Then let the bait fall on a controlled slack line, lowering the rod smoothly with the lure as it sinks and smoothly winding in any slack line - always expecting a bite to come on the drop. I'd strike (just a sharp movement of the wrist) at any tap I feel on the way down. In between lifts, I'll occasionally just shake (literally, just quiver the rod tip - with a direct line to the lure), to slightly move the bait as it rests on the bottom. Maybe 10 seconds later, I'll repeat the lift again and watch for a bite on the drop (don't rule out bites while its sitting static as well though, so keep a tightish line).
Truth is though, it's different almost every time as you can allow less or longer pauses, smaller lifts, more shakes and less lifts etc. You obviously don't even need to let it touch bottom if you don't want to, but the same pattern has been successful for me in all sorts of guises.
It may not be 100% the same for all straight tailed soft baits, but that is what I find with XLayers. Bearing in mind the rattle may play a part too - especially with thye 'shake' I mention above. Try it out in a rockpool and try all sorts of tiny movements.
Rule no.1: Don't fish it so the bait is going absolutely crazy (although you'll still catch fish - just fewer and smaller). Split your time between gaining a fish's interest (with no or tiny movements), and then actively fishing for a bite (on the drop).
It's different for everybody though so you'll get other answers too
p.s. that's mostly with jigheads between 3 and 5g. In shallower water you can obviously rig them weedless on weighted or unweighted hooks. Again, don't go crazy with the movements. Just give it one or two very subtle twitches and let it slowly sink and do it's own thing.
