Any of the herb can be cut back to produce more stems . Just use a sissor and cut them down a few inches . Also do this to your mum plants if you have them .

Do you pinch the tomatoes back to just one or two leaders?

Sometimes I do and other times not. Maybe this year I'll pinch half of them and let the others go, just to see what might happen.

I've done both with the Tomatoes, doesn't seem to make much difference to me.

In the 80's, my dad grew the biggest tomato in NJ. He won $50 and a hat. He always pinched them to a single leader.

I was tickled because he used my mom's old bras to support the heavy fruits.

I cut oregano and marjoram after flowering (leave it for the bees) but many cut back just as flowers form (to make more leaves) I don't know if "pinching" is necessary but it couldn't hurt (and would is that what you want? make a more compact plant?) besides you can always eat the thinnings. Basil can be pinched but I don't find it necessary. My cilantro bolts so fast I don't pinch (i.e. don't want to hinder ANY growth) it much if at all. Never grown peppers of pumpkins. There's been a big debate (check there) on the tomato forum about "pinching" although most have decided against it. Sometimes its tempting to "tend" your plants to much but sometimes (often) in gardening less (of that sort of thing) is more. :)

Another novice here.

When you cut the cilantro after it flowers, how far back do you cut it? Mine has bolted and is flowering now. Also, would like to collect the seeds for use in cooking and to put away for planting next year. When/how do I do that? I would really like to do that for as many things as I can in my garden.

Oh and can you pinch back bee balm after it flowers to get new growth, or once they are done, thats it for the season?

Once cilantro goes to seed, its done. It will die off. Some of mine have died off already.
I cut my bee balm way down. I think I get some reflowering but nothing great.

On cilantro, it's really easy to see the seeds. Let it flower, and the flowers will finish. Eventually, you will see a little brown ball where the flower used to be. That's the seed (it's sold in the markets as "corriander"). I let mine dry on the plant, and then shake them off into bags for saving. I also get a volunteer cilantro plant or two each season.