Here is a great guide from Columbia University, “Completing Your Dissertation Without Tears.” (Though it is a little late for me on that front.)
Some good tips:
It also reiterates, clearly, what you should be doing (which is all to easy to forget):
Your argument should grab the reader’s attention. It debunks a myth, corrects a misconception, enters a debate, or challenges a popular interpretation. Be prepared to explain the significance of you topic succinctly and compellingly.
There are some other good tips for getting over common problems, like having nothing to write. Overall, this is a good pick-me-up if you’re stuck.