This page will focus on different propagation modes, which are of interest on 50 MHz, but they can of course be found on other frequencies too. Depending on propagation mode the distance you can cover will be different, which makes all of them interesting and useful. The first frustrating thing on 6m is that you have propagation modes interacting, so it can be very hard to define the actual mode or modes used. I have heard LU stations with auroral tone and the guess is that I used the aurora at first and after that F2 for the longer path. In Sweden we often need sporadic E to southern Europe and there we link with TEP or F2.
The second frustrating thing is that most of the openings are very hard to predict, which creates the need of 24/7 activity the first 365 days of the year. Monitoring the activity on the sun will, however, give you some indications on what to expect propagation wise. Here you have a site that gives you a good picture of the solar activity.