Good tomato pruning tutorial here:
https://bonnieplants.com/gardening/how-to-prune-tomatoes/
Please note: Pruning is suggested for INDETERMINATE varieties, the ones that keep growing and setting fruit until frost. You can pretty much leave your DETERMINATE tomato plants alone, which are the ones that set fruit all at once, then are done.
https://www.bigblogofgardening.com/prune-tomato-suckers/
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Thank you for posting!
additional information! (Which I just learned from the linked site!)
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“Suckers grow in sequence, from the bottom to the top of the tomato plant. The higher up on the plant a sucker appears, the weaker it is, due to a lower concentration of sugar. Tomato suckers are especially assertive in the heat of the summer when the plant is producing lots of fruit, so be diligent and keep pruning, because the suckers are siphoning off nutrients from the rest of the plant.”
(And this, which I knew!”
“There’s also a second method of pruning tomato suckers, called “Missouri pruning”. In this method, you remove all suckers that appear below the first fruit cluster. For all other suckers, let them develop two leaves, and then pinch or prune off the tip. This will stop the growth of the sucker, but allow the leaves to remain, which shades the tomato fruit below and aids in photosynthesis. Shading the fruits is helpful in avoiding sunscald.”
If you have hot humid summers with lots of sun....