+1 to Nos & Henry's descriptions.
To add to the soup, I trim in (but not fully) to get from 0 -> plane, then trim out until either the prop starts ventilatiing at the slightest excuse or the waves are getting too hairy.
Sounds wolly & imprecise? Yep it is, BUT as also said above, when it feels & sounds right, it probably is. As you trim out (slowly at first until you get the hang of it) you will hear the engine note change from labouring to "free singing".
To put this in perspective I retro-fitted PT to mine, and never got round to fitting the trim gauge sender to the engine -my gauge is still not connected & I trim purely by feel & audio.
So there's your excuse to go & play!