I'll definitely look thru those links.
So much to learn! But fortunately, I've several volunteers (Cherry, Black Cherry, Mulberry, Red Maple, Sweet gum, Rose of Sharon, European Plum, and Siberian elm) in my garden that I could probably experiment with. (Eventually, I think it would be kind of neat to create a grouping in a natural plant community -- not the E. plum or S. elm obviously -- with some moss or maybe sweet fern to look like understory fern....) There's some kind of a very old (4" trunk diam -- too old?) dwarf/weeping/trailing blue spruce (only 5' or so tall, growing sideways with spread of about 6') that needs to be moved/removed -- Spruce looks to be an "advanced" subject so I'll just start by "pruning" it lightly this winter to see what it does and maybe I'll trench a root quadrant. If I can manipulate its growth/form/habit in the ground, then I'll consider it a possible future candidate.
I've root trenched a couple of 3' and 4' cherry and Siberian elm saplings. Should they be potted in say a nursery azalea pot now, or should I wait until spring to pull them out of the ground at all? Would that be done while they're dormant? (I should tag them if that's the case in case I forget what/where they are) The little 5" seedlings, Rose of Sharon, and European plum, I'll definitely wait until spring to dig up. They'll be fun to just experiment with since I'll have no fear of lopping off their heads or cutting up their roots.
I'm researching but it seems to me that one of the more difficult aspect of this hobby would be to properly overwinter the bonsai that are in shallow trays.... I don't think I'll actually start unless I know I have adequate method for protecting them --- I'd hate to lose them after all that work and care have gone into them. Also, how do you keep the trays from freeze damage/cracking? Are they only put in the pretty trays for show (i.e. "Enjoyment" during peak leaf, flower, or fruit) -- do you then put them back in "training" pots?
Some of the more bizarre (to me anyway) techniques I've seen so far in the link I posted:
2000/06/06 [Work] Stalk cutting -- would you DARE chop up seedlings like this!?
2000/06/04 [Work] Leaf Cutting (3)Yama-momiji(Acer palmatum var.matsumurae) -- I thought THIS was drastic until I saw these:
(these are in the Japanese page of the blog (daily discovery/observation/work/enjoyment -- Japanese page goes to  entries)
 Reshaping Acer
And I thought this was a really simple way to enjoy seedlings -- I might try it with some of the maple and sweetgum seedlings:
2000/05/22 [work] The seedling of this year is planted on the rock.
-- Of course *I* don't live on a volcanic island so I'm not going to find a rock like *that* lying around "while walking along a mountain road"