I have a few shots that include the trees that tend to be pruned the most. I have not been able to get shots of their recent (last week) prune but theses are from last year and they were pruned a little after the pictures were taken so you can see that it has to be done twice or three times a year especially with some so called 'slow growing' species!
I use heathers for bushes and various dwarf/small leaved evergreens for simulating firs or deciduous trees. Some species are really nice and easy to make into single 'convincing' miniatures of their larger cousins but others tend to have the appearance of a small clump of trees as they will have multi-branches from the bottom of the stem.
Of course you can selectively remove branches to leave nice bare trunks on any specimen but the multi-stem versions can look a little too 'nude' if they have only one stem left. But, saying that, one or two 'spindly' ones do make a nice addition.
My intention was to have green all year around, much like in the the garden as a whole, so the evergreens were chosen with this in mind. The species that tend to make the best 'specimen' single trees are:
Picea Glauca this is the one that can be made into great looking simulations of life sized firs like on Richie's layout. I have a couple but I manged to kill off two others as I sited them where they did not get any moisture...a bad move with any fir but especually Picus as they get red spider mite real bad! Good selective taking out about every second branch as you go around and up is the best way to prune these.
cryptomeria japonica this is a lovely little bush. I used it by the garage scene and it can be shaped into convincing deciduous shapes
Chamaecyparis Obtusa 'Kosteri' this is the one by the coaltower and oil fuel tank. It can be shaped and pruned into a convincing deciduous tree
cypress Hinoki or 'false cypress' this is the one that is by the water tower and engine shed. It takes on the look of a miniature scots pine if just pruned to leave the trunk exposed. It is commonly used as a bonsai.
dwarf chamaecyparis this will need pruning at least twice a year or it will get out of hand. It is top left in picture 6
Have trimmed several of my trees to keep them to size 
