We called it the Rubber Duck method of debugging. It goes like this:
1) Beg, borrow, steal, buy, fabricate or otherwise obtain a rubber duck (bathtub variety)
2) Place rubber duck on desk and inform it you are just going to go over some code with it, if that's all right.
3) Explain to the duck what you code is supposed to do, and then go into detail and explain things line by line
4) At some point you will tell the duck what you are doing next and then realise that that is not in fact what you are actually doing.
The duck will sit there serenely, happy in the knowledge that it has helped you on your way. Works every time. Actually, if you don't have a rubber duck you could at a pinch ask a fellow programmer or engineer to sit in.
A university in Canada I was told about many moons ago actually had a teddy bear sitting in the student admin's office. When a student wished to book in with a lecturer to discuss a problem they were asked if they'd explained their problem to the teddy bear. If they hadn't, they were told to do that first. This cut something like 80% of lecturer meeting requests from students.