This type of scenario is one that always gives me chills. There have been so many cases I've followed over the past 30+ years which involve the person who does work on the home/property/rental being the murderer. Men can be targeted, but I believe women living alone are more vulnerable due to statistics showing that most violent crime is committed by men, and people that do jobs like property maintenance, home repair, etc, are more likely to be men as well. (Of course women can commit crimes, so its not black and white).
I understand how people end up feeling like they can trust these folks. Its not always easy to find someone to do the task/repair you need, when you need it, at the price you can afford. Or you may be required to use a certain person if you're renting. Or a friend can recommend someone and not know the person has a bad side to them. This is the case of many ponzi schemes where the perpetrator infiltrates a community and so everyone trusts them and refers their friends and family to the person.
Ideally, some ways to decrease the odds, in the case of home repairs, I think would be using certified/licensed/bonded local companies, checking reviews, ask about background checks on employees.
Taking it further, if a woman does live alone, perhaps dropping comments (which could be lies) about their uncle, cousin, brother, son, friend, etc visiting. Saying something like "We can schedule for next Thursday at 4pm. My brother is coming into town that afternoon, but he can make himself comfortable while you do your work,"
Or have someone else with you while they work in the home. Pretend to take a phone call when they show up, "Hi Frank, yes, Bob the plumber just got here." Then ask Bob "how long will you be?" Then, "He'll be here until about 2pm, I'll text you then so you can come pick me up for lunch." Or the classic, put a pair of dirty men's work boots near the front door.
Never share any personal information with them, definitely never make comments about your finances, hide any prescriptions if you take any that can be abused. Keep a very strong boundary around sharing any actual personal information that could be attractive to a potential criminal.
Maybe some of that sounds a bit silly, but I think predators often look for easier targets, so if you can paint an illusion that other people are around, might be around, will check on you, etc, why not?
None of this is to blame the victim. This type of crime really gets to me because these people prey on someone's vulnerability. And we're not always in control of how vulnerable we are. Years ago I never thought much about the "handyman commits murder/rape/theft/etc" scenario, but after reading so much true crime, its something I've become much more aware of.