What should one do upon suspecting a bed bug infestation
The first question I would ask that person is, what makes you think you have bed bugs? A skin reaction alone does not necessarily indicate the presence of bed bugs. Other bugs, allergies and irritants in the environment can produce similar skin reactions. And it's hard to confidently identify a bed bug bite because reactions vary from person to person. My next question would be, have you seen an insect in an area where you sleep and, if so, was it the correct size and shape to be a bed bug? Carpet beetles in an immature stage are commonly mistaken for bed bugs. The carpet beetle actually doesn't look anything like a bed bug, but it is the right size. And it's another common insect to have indoors around the bed. If you find an insect that you think is a bed bug, save it in a pill bottle or another container so its key characteristics won't get crushed and a professional can identify it.
I wouldn't try to get rid of an infestation on my own. I would call a pest control operator. A good pest control operator will spend a fair amount of time inspecting the place for evidence of bed bugs, and will educate the person on what makes it clear that it's a bed bug infestation.
Once you have a suspicion or a confirmed infestation, do not spread things outside of the bedroom. Don't take linens off the bed and go to sleep somewhere else—that will just move the infestation to other rooms. Ultimately pest control operators will tell you to put everything you can through the washer and dryer, since bed bugs cannot withstand high temperatures. I don't think bed bugs would be able to survive solvent-based dry cleaning, but I don't have any first-hand knowledge that that's true. Unfortunately, dry cleaners and Laundromats can be places where people pick up bed bugs. I think it's a low probability, but it only takes one adult female bed bug that has been mated to get an infestation going.
The safest and most effective approach to getting rid of bed bugs is heat treatment, in which a trained professional heats the home's rooms one by one to a temperature of 50 degrees Celsius and sustains the heat for four hours. Heat does not penetrate well into wall voids, though, so desiccant dusts are often applied to those areas. No single technique can eliminate bed bugs—combinations of approaches are essential to getting the job done.
What are the mistakes people make in trying to get rid of bed bugs on their own, without professional help?
DIY approaches come with risk. It's not uncommon for someone to use a pest-control bomb or fogger that is available over the counter. These don't work well against bed bugs, according to research from Ohio State University. They can also expose people to toxic chemicals. Neither are over-the-counter aerosol insecticides effective against bed bugs. Most of these products have either pyrethrin or a pyrethroid as a main ingredient and those compounds have the same mode of action as DDT, which bed bugs have become resistant to. If you spray the bug directly you might kill it, but that is not going to get rid of the infestation. The problem is finding all the bed bugs. Some just can't be reached with insecticide. It's difficult for nonprofessionals to do anything more than kill what they can see, but that's just the tip of the iceberg in terms of what's there.
Some of the dusts that are available to consumers, such as diatomaceous earth, can help in this regard. Pest controllers will put dusts in wall voids and other places where pesticide won't reach. What happens is the bugs will wander through the dust and pick up particles and be more vulnerable to desiccation after that exposure. But dusts will not solve the problem if deployed incorrectly, and if they are applied at too high a level they can cause breathing difficulties in some people.