Load boards

Im a company driver and I've realized I actually love trucking. It's working for a company I hate.
(I've been self employed or a lead most of my life)

It will be a while before im ready to take the leap. Hell the stars have to line up.

Are there any decent load boards out there I can use to look at the rates?
I've looked at all the free ones but the rates are so cheap I can't see anyone hauling the freight for that.

How do you figure your cut off point? Is it when you're breaking even (to me this sounds more like losing money) or is there a minimum profit margin you set.

I looked into it and if I use worst case scenario expenses, there's no way in hell I'd haul freight for 2.85/mile like I see posted on all the free load boards.