Me and my dad have always collected.Have done the best on hills near water.But have found them far from water too, where you wouldn't have expected them to be.

Also look for spots in the field where you see an area that is darker than the surrounding soil. Campfire/refuse discarded over the years makes the soil dark. Invariably these areas will be near water, or where water once ran. Out our way 90% of the arrowhead are made of obsidian so those are the flakes that I look for. During my younger days I found them by the pocketful after the first fall rains.

Beaverpeeler, brother Phil and I have had many a talk about arrow heads, relics and metal detecting. The advise you just gave is spot on and provided some great success in my hunting.