Bill Tindall, E.Tn.
A sharp card scraper levels a run the best of anything I have tried.
Solvent based finishes have a substantial advantage when it comes to run prevention. They will be formulated with a mix of solvents of different boiling points. When the finish hits the target the lowest boiling solvent quickly evaporates which dramatically increases the viscosity of the film. Higher boiling solvents hang around long enough to promote leveling.