A lot of people have already mentioned many of these things, but here's a list, anyway, of things that can help promote better sleep.
I think a set bedtime routine can help. Try to go to bed at the same time every night. Take a warm shower or bath before bed, if that will help you unwind. A glass of warm milk can really help to promote sleep. Reading in bed will generally help me to become drowsy. Sometimes I will take melatonin, and my doctor told me it is safe as long as I don't take it nightly for more than three weeks.
Since you are under stress, it's important to clear your mind so you can fall asleep. I often use imagery to turn my mind off. When I'm ready to nod off, I close my eyes and I imagine I am alone on a beautiful beach, in the warm sun, with a gentle breeze blowing. I really try to feel the warmth of the sun and the breeze against my skin. If thoughts come into my mind, I imagine them washing out with the waves. I try to concentrate on feeling physically comfortable and relaxed, while making my mind as blank as possible. Sometimes I will imagine I am swimming underwater, near the bottom of the sea, and observing colorful fish swimming by me. I concentrate on the feeling of swimming and what I am observing, and I don't think about anything else. You can use imagery to put yourself into any situation which might be relaxing for you, and then enjoy being there and not thinking about anything else.
If I can't fall alseep in 10 or 15 minutes, and I start feeling upset about still being awake, I get out of bed. Either I will sit in a chair and read or watch TV, or I will go on my computer. On the computer I'll generally read something like the NY Times until I start feeling tired or sleepy. Sometimes I'll come to A2K and play the trivia games, or, I'll go to a game site and play something like Text Twist or Bookworm until I begin feeling tired enough to try getting back into bed. I don't do anything that really requires a lot of mental energy or is likely to make me feel more awake. But I do things which are mildly distracting if something is bothering me and keeping me from falling asleep (in my case, it's usually back pain). When I get back in bed, I might listen to some relaxing music, or I might put something on the TV that I really don't have to pay attention to--like CNN, or some other cable news station. I sleep better with some background noise, so I generally leave my TV on all night, but tuned to a station I can basically ignore and I keep the sound relatively low. But, don't stay in bed tossing and turning, if you can't sleep. Get out of bed and do something else--but something that will help get you ready for sleep.
Try to get yourself on schedules during the day. Eat properly and regularly. Go walking around all the small shopping centers and business areas you can find for some exercise and to see if anyone has help wanted signs in their window. As bad as the job market is, I regularly pass stores and businesses and restaurants that have signs up looking for help. Consider doing volunteer work at an animal shelter, if you like working with animals. You might not get a salary out of it, but you might wind up with a reference to help you get a paid job, and it's better to be busy while you are unemployed. Your local library might also need a volunteer.
Good luck with everything. I hope you find a job soon because that will certainly reduce your stress level. But, getting better organized and less "random" about things will also help you feel better. Get control over those things you can control.
Insomnia is miserable. I think we can all commiserate with you about that. I really hope that some of the tips you've gotten will help you.