There appears to be a discussion about whether to use the ruler or the mat markings for measuring. My opinion is that it really doesn't make a difference UNLESS you are using both in the same project. Decide which one and use it throughout. Yes, there may be just a thread or several difference but, as long as you consistently use the same method, you will be ok. Use either the ruler OR the mat markings; not both in the same project.
Maybe someone else has already suggested--if you have difficulty threading the needle, most of us dampen the end of the thread with saliva. Try doing that "spit method" on the needle itself. It's amazing how easily the thread goes into the eye of the needle.