Here are a few tips from Jeremy Riggs via a couple online resources and from a couple things he told me that were really helpful.
Links are at the end and I'd also check out Jeremy's website Paddle with Riggs dot com.
From Elder SUP: 1) The key thing is keeping up your momentum. Shorter rapid paddle strokes keep momentum going – keep speed up.
2) Don’t go right up the back of the wave in front of you – that will slow you down as you paddle UP(hill).
3) Look for the place to keep the momentum going, a place to guide the board into the trough where you can catch the next bump – and have tons more FUN!
From me: 1) The reason paddlers get tired is they paddle too much. Don't paddle when you can't go anywhere because you're fighting the ocean. The ocean will win. Don't knock yourself out. Focus on catching the next bump.
2) Don't take too many strokes on one side of the board. That can easily lead to the tail sliding around and you will fall off. Jeremy's "rule of thumb" is no more than three on one side before switching.
3) One more like #2...be ready to switch paddling sides quickly to not only change direction (and catch or stay with the bump) but to keep from sliding out.
4) Be ready to back peddle quickly when you catch a steep one so you can keep from pearling. You have to be fast to the tail and then quickly move forward again to stay in trim and stay in the glide. (Standing too far back on the tail is like putting the brakes on.)
5) Don't just watch the nose of the board, a good downwinder is constantly looking around, left and right, seeing what's coming in the smaller bumps to gain speed in order to catch the bigger, longer glides.
#5 was the hardest one of all and where Jeremy's coaching is essential. During our session he was constantly calling me into bumps that I didn't even see. But this skill isn't something you'll learn overnight. It takes time and practice. The cool thing is that it's really fun learning and no worries, you WILL catch bumps!