I am now editing my chapter titles. I will keep them short. I have been guided by some of the best examples of contemporary literature. Two to four words appears to be the average. The less said in the chapter title the better. It is better to keep the reader in suspense than to spill the beans. My chapter titles will merely act as a basic signpost to the reader.
I have them in my first draft, however, I used them more as a signpost to myself when writing the chapter.
Once I have finished with my edits, I will remove them, as I do not think they are terribly necessary - I also think without them adds a bit more mystery.
Joanne Harris uses dates to excellent effect in Blackberry Wine
The Day, Month, and Year are good signposts.
Some authors use symbols, quotes and poems.
I've not used chapter titles as such - I've not seen the need. And nowadays they seem more common in non-fiction.
My two stories are broken down into parts, with those split by date (year or month). The second has certain chapters headed by placename, but these locations may include one or more chapters before the action moves on. Because I write fairly short chapters, often from a single character's POV, I thought readers would follow it more easily that way :)