While I am not certain i am aspie, so I don't know if this really relevant ... it depends on what it is that I'm having trouble getting started with. If its a routine behavior, then I've found doing it in a routine way or at a routine time usually helps. For instance, lets take making food - then I typically eat around the same time every day, and that makes it easier to do it. Otherwise, if my schedule gets thrown off for some reason, I often will forget to eat or will sit there and be hungry and will just not eat.
I have also found, beginning new things is often easier at standard transition times. I.e. at the beginning of an hour, at the beginning of a day, a the beginning of a week, at the beginning of a year. So I plan accordingly, and will usually only attempt to begin an activity if its at or around the beginning of an hour. This can be very frustrating for normal people though, but then I usually let their motivation pull me along.
And that can be another one. Letting other peoples motivation pull you along. Of course, that requires socialization, which isn't always fun, but ultimately required of being human.
Duty and responsibility tend to be good motivators for me as well. I have found, if I have a responsibility to another person to do something, then I am much more apt and able to achieve it. Projects I have started for myself tend to languish for years, where as tasks that I am doing for other people get done quickly.
I think this is often because things done for other people usually have a clear scope and objectives, where as things done for myself tend to have the nebulous objective of somehow pleasing me. I do best when I have a very clear set of objectives. A set of vague goals leads to vague success, and I'm not always very good at solidifying my goals... even when I try, it then often turns into a project to figure out the project. Meta-projects. I still end up just being frustrated. I have found journals and writing tend to help with that, but they tend to also take a lot of time, which can be frustrating itself.
So I don't know if any of this helps, but if I think of anything, I'll post it.