The podiatrist suggested I try orthotics for my flat feet. Is there any way to tell if they will work before I spend the money on it?

There are some times when orthotics or special shoe inserts offer foot comfort for people with flat feet. Many people do just fine with just a good arch support in the shoe. It
depends somewhat on the type of flat foot you have and how severe it is.

There are some taping methods that can be used temporarily to see what effect support has on the arch. If taping the arch improves your symptoms, then it's likely the orthotic will have a positive effect.

Taping has been shown in studies to reduce the pressure through the bottom of the feet. It also distributes the weight more evenly from front to back and side to side under the foot. This is especially true when the flat foot is accompanied by a significant (10 mm
or more) drop of the navicular bone.

The navicular bone is on top of the foot about where your shoe laces tie. There's a bump on the bottom of this bone on the inside of the foot just above the highest part of your arch. In many people with flat feet, the navicular bone has dropped down. Taping the foot so the navicular bone is in a neutral position will help guide your orthotic decision.