Ask for a written quote naming the guard type and material, the price per foot, the feet measured, and any cleaning or repair before installation.
Ask how the guard fastens: inside the gutter, to the gutter lip or fascia, or under the first course of shingles. Guides warn that under-shingle designs can affect a roof warranty, so read yours first.
Ask how often the company expects the guard to need cleaning under your trees, and whether the maker’s warranty depends on professional installation.
Before anyone climbs up, get proof that the company carries liability insurance. SirGutters lists companies from what their websites say and doesn’t look into licenses or coverage.