I'm taking part in a campaign soon and the GM has given their blessing for a custom tradition for a shaman.

I was super intrigued by the more city oriented spirits from Forbidden Arcana and I want to build a shaman that works with wild spirits like the vehicle or airwave spirits.

I understand wild spirits cant be summoned as such and that you basically have to talk them into helping you or earn spirit markers. is there anything else I should look into/consider if I'm looking at a shaman for wild/city spirits?

I'd suggest having one or two as contacts, to increase the character's ability to get in touch with at least some spirit regularly. And probably one or more knowledge skills related to the local free spirits, to justify knowing who to call on.