Find out what your friends know.
I had a friend that wanted to switch to Linux. When he asked, I told him I could probably help with any distro he liked, but I really knew Ubuntu having used it for years. (I was just starting out on ArchLinux at the time)
He felt alot more comfortable using Ubuntu for that reason. Having personnally solved a multitude of "noob" problems along the way, some Ubuntu specific, his transition to a Linux OS was easier.
To know someone versed in a specific distro will make distro a better choice to start with. That friend probably had the very same problems when he/she started on that distro and solved them, making your life easier.
Of course, if you have no friends (that uses any distro at all), you're not going to consider this point at all.
