Your question is interesting (not from a personal "I want to think about suicides" point of view, mind, because I'm most certainly not like that). Right from the start, I will say that I have no idea what any definite known causes for the recent spate of railway-related suicides are/were, and whether or not any particular cause has been identified as a theme. I'm sure economic uncertainty may be a valid explanation for some of them, and it does seem that a lot of suicides occur closer to the winter equinox.
What can be done? That's a really tough question to answer.
I know that some stations now have posters and phones linking to organisations including the Samaritans, which is a good idea, in my opinion.
Technological improvements such as platform-edge and passenger-side doors are tricky to implement where more than one door layout is in use (for differing classes of trains), so many mainline railway stations are unlikely to see these pieces of equipment. Someone on the forum recently suggested roller blinds to prevent unauthorised track access, and I identified a number of design problems with these, but it's an interesting idea.
At stations such as Purley, you'll find fences (with gates for stopping services' passengers) preventing any suicides from fast line platforms with few stopping services, but this is impractical for many stations with greater platform flexibility. Desperate people might also vault the fences or jump in front of slow trains.
It might be interesting to see if stations with ticket barriers have fewer suicide attempts, but I should think this would be a very weak correlation. Barriers may, however, prevent "spur of the moment" actions.
Perhaps passengers could wait in concourses until trains are due, with access barriers then opened, but overcrowding would probably become an issue, and many stations are unstaffed and do not have sufficient waiting areas.
As for preventing accidents, I think we need more education and greater numbers of staff on platforms.