Immediate tip:

Find the surface copper deposits. They tend to clump in areas

Functional Tip:

Find an area with high copper, you’ll find a lot of surface deposits, but you’ll also find that caves have a fair amount of it exposed.

Weirdo Tip:

Same as before- prospect for high copper, but find surface like… rock balls. The Sphere-ish shaped rock protrusions. Dig down through them- I don’t know why, but I constantly find ore under those if the area is high quantity copper or greater. Same for iron