My two cents

In the latest volumes of the Service Design Principles series, I try to stick to this formulate for my titles:

1. Always start with a verb to show the action we should take

2. Write it as if it was a piece of advice given to you by the people you serve

3. Don't use business lingo in it, and say it in the words of someone who doesn't know shit about prototyping, strategy, service design, etc.

4. Keep it as short as possible

How others do it

Blake Snyder, the author of the screenwriting book Save The Cat, names his own principles (which aren't Service Design principles but screenwriting principles) with what I would call mnemotechnic titles.

For example, one of his tips or principles is called "The Pope and in the pool". In it, he explains that to create a good story, you need to give a lot of information, but this can get really boring. So in one film where the Pope is the hero, the key information is given by the Pope's counsellors, but this time it's done while the Pope is swimming. And that makes this moment less boring because nobody ever saw the Pope in a bathing suit...

Ray Dalio, in his book Principles, often also starts his principles with a verb, and they also feel like pieces of advice someone would give you.

The people of 37signals who make Basecamp and Hey have a mix of mnemotechnic titles and advice which start with a verb in their company's principles.