I've noticed I'm having trouble with projects that repeat each week but don't have a particular due date, for instance: "Blog twice a week for my client." It doesn't have to happen on a particular day, but should happen twice each week. I usually wait until I feel like writing or see something that would be appropriate to blog about, but then other stuff gets in the way or I don't feel like it, then poof, end of week and no blog posts.
I like schedules and Standard Operating Procedures.
I blog twice a week and my posts appear on Monday and Thursday before 7am.