The very best thing you can do is keep the tank full of diesel. Don't wait until the tank is empty. By displacing the air with fuel there is less chance of condensation and corrosion of the fuel float. A lot of people like the stuff in the White bottle.
^ What he said.
Best practice for diesels has always been top up the tank at the end of
every operating day. That's even more critical (IMO) for the hobby category many of us fall into..... you pull it out for a project, then at the end of a long day think "I fill it up tomorrow/soon..." - next thing you know days or weeks go by....
Read, read, and read some more on additives..... lots of discussion out there. After my research, I settled on Stanadyne a few years back - there are other good ones out there.
What's probably at least as important is
where you buy your diesel from. Generally, the best choice is a HIGH volume truck stop - you want really fresh fuel - where I buy mine will sometimes get 2 tanker train deliveries a day.
Diesel that sits around can collect water, and esp. today, that easily leads to microbial contamination (algae). Treatment for that includes biocide addition - be aware of what this is, but don't go there unless you need to.
Esp. if you rely on your tractor (clearing snow, downed trees....) keep at least one spare fuel filter at home. Many of todays compact tractors have a small single stage filter, that can plug up relatively quickly. Winter use means a risk of frozen filters (esp. w/o additives), one more reason to keep spare filters handy.
Synthetic oil and a block heater are also a great way to get through Winter successfully.
Rgds, D.