Step 1: ...should this be 'don't campaign'? Because I think that there are quite a few of us who think Step 1 ought to be 'don't campaign'.
Step 2: If you must campaign, it's quite acceptable to 'straight talk' with voters. However, remember that ultimately, you must then ask for their vote, and in order to keep your job, they must agree to give it to you. So it helps to not talk down to people if at all possible.
Step 3: If you are contacted by the victim of a tragedy, such as the mother of someone killed in a mass shooting, be sympathetic. That's your job. In fact, that's your responsibility as a decent human being.
Step 4: Mothers of people killed in mass shootings do not appreciate it when, after expressing their concerns, they are told that they are in need of 'straight talk' while their concerns are dismissed out of hand.
Step 5: They particularly do not appreciate if your expressed need to supply straight talk is accompanied by applause from the crowd.
Step 6: If you must supply 'straight talk' to such a person, do not expect their vote in the future.
BONUS STEP: It also helps if you refrain from calling your constituents "jerks".