Troy Built Tiller Maintenance

One of the best ways is to do like people with generators should do and that start and run the engine for at least five minutes at idle speed. This refreshen the fuel in the carburetor so it doesn't become stale.
 
Another method is use fuel stabilizer but it is no guarantee against clogging as carburetors are vented to the atmosphere and fuel does evaporate over time leaving behind fuel residues behind. I even seen where the problem was the stabilizer residue that clogged up a few carburetors here.

Roy
You can also try canned gas, it is guaranteed for three years two once opened. It is expensive but for the amount you will use why worry about it.

I remember correctly that only applies to fuel in sealed container, once left open the atmosphere they will evaporate the same way. Carburetors are not a sealed containers.