I made a quick post about sql backups not that long ago. Take it for that its worth, but there is a much better way to deal with back ups. Ola Hallengren has a set of maintenance scripts that could not be easier to use. I can't tell you how much time I have spent tweaking and adjusting my scripts in the past. I knew of his scripts but never took the time to look at them.
All you do is run the script and then add a schedule to the jobs it creates. The jobs are very clear in what they do. If you review his site, he even gives a suggested schedule and job order that will fit most people. Those scripts handle many special cases. It knows if your database needs log back ups or not. It even takes into account Always On backup priorities.
I don't know why I never looked into them before, but I will use them on every database I administrate now.