The best advice I can think of is take measures so that, in case of any problem, you can go back to your old configuration while you work on fixing the problem.
- Backup your data
- Keep your data in a different partition than the OS
- Reserve a spare partition for the future distribution
The last bullet I think isn't very common, but I find it quite effective. What I do when I have to upgrade is avoid the upgrade procedure completely and just install the new distribution in a different partition while using the same partition for my home directory. This way, if the new distribution doesn't work for me, I can either look into the problem and try to fix it or, if I need to do some other thing, use the old distribution.
I've never had any serious problem; but, at the same time, I've always been sure that in case of any problem (drivers, configuration, etc.), I could go back and use my old stable configuration as usual without any danger to my personal files.