Excellent advise.
While I do not suggest it, I had a friend who sent a letter in crayon. He was making a point.
It’s important to subdivide legislators into “friendlies you support” and “intransigent enemies who need to feel electorally threatened.”
An excellent example of the latter are those legislators in Colorado who are now unemployed.
More than anything else, friendlies need moral support because while they get pounded on by lobbyists a lot, they crave to know what their constituents think. If their voters support them, they feel a lot more confident in supporting their beliefs and are less prone to manipulation.