Will these cut stainless steel or aluminum sheet, or should I stick to mild steel?

Straight-pattern snips work best on mild steel up to moderate gauge. Stainless and aluminum require compound-leverage snips to reduce hand fatigue — check the thickness of your material before committing to straight snips.

How do I know if straight-cut snips are what I need versus left or right cutting?

Straight snips cut in a true line — no deflection left or right. Use these for centerline cuts (fender seams, roof panels). If you're trimming edges or curves, left or right snips will feel more natural. Straight is the most versatile for patch panels and flat work.

Do these need maintenance after use?

Wipe the blades clean of metal debris and oil after cutting. Keep the pivot nut snug — if blades separate or start binding, tighten it slightly. Store in a dry space to prevent rust.