I'm afraid that this tip is so simple and obvious that it hardly needs saying. That didn't stop me forgetting all about it.

It is this:

If your laptop has nearly run out of juice, and you have the opportunity to charge it, then charge it.

See? I told you it was simple.

The circumstances that led me to share this ground-breaking, not to say earth-shattering, tip are as follows:

1. Last night my laptop charge was down to 9%.
2. I thought about putting it on charge, but didn't like the idea of leaving it charging overnight unattended, so I didn't.
3. This morning we awoke to a power cut. With no laptop charge to speak of, it played havoc with my work schedule. (Even worse was the impossibility of a cup of tea, but that's another story.)
4. As a result, we had to go to a cafe for breakfast, and then on to a library to plug the laptop in and get on with some work.

The moral: given the occasional exigencies of various services, such as the electricty supplier, if you get the chance to charge your laptop, phone or anything else, just do it.