Tip #1 Keep a Diary
I am constantly amazed how many people with better memories than mine (OK, that's just about everybody) ask me when certain things happened on our project.
Nowadays, despite the plethora of software aids, no one seems to keep a diary. Maybe if someone were to write a sexy app for the iPad then more people would keep a diary, but actually all you need is a word processor such as non-sexy MS Word and the determination to keep it going.
Actually my diary is a simple Word document written almost as a stream of consciousness, but I am careful to break up the stream with dates (and sometimes times).
I note everything that happens beyond simple task completion. I also leave minutes of meetings to the experts, but anything else is fair game.
By 'anything else' I include all personnel matters, deliveries of hardware and software, visits by sponsors and customers, decisions made or rejected, achievement of milestones and deliverables, and so on.
Some of these things are obviously included in project plans and progress reports, but many are not, and to have a record of all activity can be very useful.
I spend just a few minutes every day recording what happened. My best time for this is early the next morning, but I can see that a better time is at the end of each day. However, I am often so desperate to 'get out of this place' that I have developed the morning habit.
And that leads to many of my younger and fitter colleagues relying on my diary...