My focus here is on unusual sorts of harassment, such as through electronic or chemical means. If your problem is a familiar sort of harassment, such as sexual harassment or bullying, then you should check the vast array of relevant material.
You may have raised your concerns with various authorities and received a brush-off. What to do next?
There are three main strategies:
To get others to take notice and do something about the problem, you need to convince them that something improper is occurring.
Harassment does occur, including through unusual means such as electronic beams. But it isn't all that frequent. Just add up the number of government and private agents and the amount of time they have to spare, and it turns out they can't harass all that many people.
Are you an obvious target? If you are an intelligence agent, a prominent radical or a big-time criminal, harassment is more likely. If you haven't done anything spectacular to warrant special attention, why should you be singled out for harassment? Others will ask this, which means that the less obvious a target you are, the better the evidence you need to obtain to convince them.
What do you need? Documents, photos, chemical analyses, measurements of magnetic fields - whatever it takes. If a helicopter is above your house, then step outside and take a photo. If people are following you, use a miniature camera to record their movements. If chemicals are being applied at your house, take samples and have them tested.
Once you have convinced some other people, get them to advise you on the next steps to take.
If you can't obtain good documentation, then you won't be able to convince others that anything is happening. So consider options 2 or 3.
If you are a really big-time agent or criminal, you will have a good idea about surveillance and harassment. If not, it is almost certain that you will not be watched or harassed all the time.
Take a day's excursion or a longer trip away from your usual routine. The harassment should be gone, at least for the time being. If not, consider option 3.
If you can't escape the harassment and can't convince anyone that it's occurring or serious, then you might as well learn to live with it. Just carry on your daily activities and don't let anyone know you're the least bit disturbed. If you seen unfazed, harassers are less likely to bother you.
A useful source of advice is H. Michael Sweeney, The Professional Paranoid (Venice, CA: Feral House, 1998), which tells "how to fight back when investigated, stalked, harassed, or targeted by any agency, organization, or individual."
Brian Martin's website on suppression of dissent
in the section on Documents