Yes, we find that putting the tank on straight is a good way to go.
Always push the foam seal onto the outlet of the tank, before setting the tank onto the bowl. Keep the tank aligned while tightening.
There is the rare occasion when the inside of the tank is cast rough enough where the seal just below the flush valve will not seal.
A little emory cloth will smooth the porcelain and it can be reassmbled.
If find this to be very rare. Maybe one in a hundred.
I followed up on a Drake tank installed by another plumber that was loose today, 10/22/2008
The tank nuts were "finger loose",
I took out a wrench and tightened them "wrench tight"
No more loose and wobbly tank.