Picking herbs is good for the plants

Parsley

Sometimes I forget to pick herbs, because I think I'll wait until its needed for dinner. Then I burn dinner because I go out to the garden to pick herbs and find other things to pick or weeds to pull. I planted herbs in planters near the house, but they didn't do well. I had to replant out in my raised bed herb garden.

Picking herbs and greens is helpful to the plants because it prevents them from forming seeds. The best way to pick parsley, and many herbs and leafy vegetables, is to snip the whole leaf and stem from the stock. Sometimes you can twist them off near the ground, especially when you pick parsley and Swiss chard.
Basil's a little different. You should cut the stock or branch, just above leaves, well below the leaves you want to harvest. Picking in late morning is the best time of day, especially for greens and herbs.
Pick leaves often to prevent the plants from going to seed. Because once they go to seed, many of the plants lose their herbiness flavor.
For Rosemary and sage, cut 5 inch branches and hang to air dry or chop and freeze herbs in ice cube trays or clumps in a freezer bag.