I have a number of different bushes and woody flowering plants in my front and back yards. These include:
Forsythia
Service berry
Snowberry
Dwarf & Miss Kim Lilac
Autum Brilliance
Choke cherry
Spirea
Lonicera Japonica
Lydia Broom
Scotch Broom
Russian Sage
Other sage plants of undetermined variety

Plants I am adding this year:
Fragrant sumac
Diervilla Kodiak
Syringa Tinkerbellle
Spirea 'Blue Kazoo'

What is the best source for information on how and when to prune them and how much to prune?

Generally, pruning is done right after blooming, to ensure that blooms are not interrupted and show up at the correct time.

Unless shrubs are planted without enough space to grow, they shouldn't need much pruning. Periodically removing dead twigs, crossing branches, should be all that is needed.

Here is a source for my confusion:
"The annual shape-up pruning routine described above is best done in late winter or very early spring before flowering. The reason: When the shrub is bare, you can really see the branching structure, and it's easier to get into the middle of the canes with your pruning tools"

http://www.flower-gardening-ma...

It really depends on your reason for pruning, and the individual plant. If you need to prune, the general rule of thumb as Tiffany mentioned is to prune immediately after flowering. The reason for that is that some shrubs flower on old wood from the previous year (and some on new wood and some on both). So if you prune in spring before flowering you will lose the flowers that formed in the previous year on the first type and it won't bloom at all that year if you prune all the branches. That particularly applies if you'd be shortening all branches, say for something that has dead flowers or fruits at the end of most branches still in spring.

The method suggested on your link (to remove a third of the branches to the base every year) is standard advice for keeping a shrub from getting too big. The two thirds old wood remaining on the forsythia would still flower and it certainly is easier to see what you're doing for that kind of pruning when there are no leaves - forsythia starts to leaf out before the flowers have fallen.

There are some plants on your list that don't usually need anything other than dead stuff removed, and at least one won't regrow from old wood (Genista lydia) if you cut too far back, as far as I recall. I'd suggest looking up pruning recommendations for each plant individually, or get a good pruning book that lists the different plants and how to prune them. For some plants the timing and method vary even within the genus, for example clematis.

As a general rule it's best not to prune in fall (more chance of fungal diseases gaining entry and causing die-back).

What I do with Russian sage is cut it back to a few nodes above the ground as soon as I see signs of buds swelling. Several of the others I don't usually prune other than dead or diseased wood (have no space limitations).

We could maybe be of more help if we knew the reason for pruning each plant.

Sooby,
Thanks so much for taking the time to respond so thoroughly. My reasons for pruning are to prepare for winter, shape, promote new growth, remove dead ends and branches. I've been very fortunate in that only one bush has had insect issues. But we'll see how it does this year.
Sadly my Russian Sage after a number of years died. I replanted the salvaged roots, but not optimistic. Usually I left them unpruned during the winter, but this year (a mild winter by comparison) they broke off from the supports holding them up.
I only grow trees, bushes, perennial flowers and a few hanging basked annuals.

Removing dead material and extraneous growth isn't something I do because it's a particular time of year, but whenever such circumstance is noticed. Removing dead material would never affect the bloom, dead branches don't bloom.

If something is distracting from an appearance that is pleasing to me, I don't wait to remove it, I want to enjoy the appearance today. Even if it's something that is about to bloom, doing that wouldn't affect the enjoyment of the blooms but enhance it, according to what my eyes want to see. Being distracted by an ugly branch, even a blooming one, doesn't please me.

Most advice about annual pruning is given with the assumption that a shrub must be pruned annually for some other reason than the spending of time and vigorous exercise, like to maintain height or girth restrictions, or are being sheared as a hedge, meatball, topiary, or lollipop.

Something like a Hydrangea, that retains dead branches, I like to trim when it's just starting to leaf out, when I can see which branches are dead. And on the live branches, which is the most vigorous node within the shape and size I want to see from it when it's in full glory. However, Hydrangeas that grow with no cultivation at all look gorgeous too. The micro-management of spring pruning is all for the aesthetic during the time before full new foliage & blooms.

You'll get to know your shrubs and develop your taste and style for shaping and maintaining them.

"I only grow trees, bushes, perennial flowers and a few hanging basked annuals."

And forgot to say, that's more than half of "everything." What else is there? Bulbs, veggies & pond plants? Have fun with all that!

Sooby,
Thanks so much for taking the time to respond so thoroughly. My reasons for pruning are to prepare for winter, shape, promote new growth, remove dead ends and branches. I've been very fortunate in that only one bush has had insect issues. But we'll see how it does this year.
Sadly my Russian Sage after a number of years died. I replanted the salvaged roots, but not optimistic. Usually I left them unpruned during the winter, but this year (a mild winter by comparison) they broke off from the supports holding them up.
I only grow trees, bushes, perennial flowers and a few hanging basked annuals.

Sooby,
Thanks so much for taking the time to respond so thoroughly. My reasons for pruning are to prepare for winter, shape, promote new growth, remove dead ends and branches. I've been very fortunate in that only one bush has had insect issues. But we'll see how it does this year.
Sadly my Russian Sage after a number of years died. I replanted the salvaged roots, but not optimistic. Usually I left them unpruned during the winter, but this year (a mild winter by comparison) they broke off from the supports holding them up.
I only grow trees, bushes, perennial flowers and a few hanging basked annuals.

What's going on here?

I prune trees and shrubs and roses right at the start of Spring when buds just start to grow, that way they get the most energy for the healthy branches, new growth, and flowers. Trees usually don't need much pruning it's just to fix, shape or remove dead/broken branches.