Forgive me for the newbie question, but I guess it fits in here:
Any tips for learning to stand and climb?

I grew up on beach cruisers on the flattest ground ever, so I never learned to stand up and mash on the pedals.

Now I've got new body position and all to worry about too. I can stand and coast, I can hover as I hop over a bridge edge or big tree root bump. I could stand and pedal a tiny bit before I went clipless when I'd start up on the bike in a big gear. But it's too easy to spin on a flat with clipless in a big gear that I haven't been practicing there--feel like I need more resistance from the gears. I figure it'd be easier to learn in a climb when I need to rev up my speed a little bit as my legs start to burn. (Now I live in a place with hills...not mountains but big enough for my newbie self and sprinter's build).

I see people do it all the time. And I get the concept of rocking the bike, but I'm worried about the sideways topple. Maybe I don't give myself enough credit. I mean, my 3 yr old nephew can stand and pedal...though ok, he has training wheels.

I tried practicing on my trainer to get an idea about what gears I'm comfortable with, but the rear tire slips too much. Tried cranking up the resistance knob but I still couldn't get smooth circles. (I can stand and be pretty still on a spin bike, with smooth circles if that helps).

Any tips are welcome