I grew up on short boards and feel like a kook when I attempt to ride a longboard, but my best advice would be to get a solid duckdive, or turtle roll in your case. If you can efficiently paddle out and get through breaking waves, you will increase the frequency of attempting to catch waves. Learning to sit on the board is important too. That will help you quickly turn around to paddle for a wave.
Standing up to me came natural. My best advice for that, and wave selection, is simply just practice. I mostly do pushups in the off season. Even at my best physical condition, I feel like I have jello arms and want to puke after a good session.
SOCAL advice: shuffle your feet when walking in the shallows. A stingray can instantly ruin your session.