Can orthotics prevent Plantar Fasciitis?

I think I understand what triggers plantar fasciitis, and so I want to know if it can be prevented somehow. I have a very active job that involves me being on my feet for most of the day and recently have started noticing heel pain and tight calf muscles in the mornings. I'm worried that this could be the beginning of plantar fasciitis and hope that there's a way I can stop it before it starts. Will over-the-counter orthotics be able to prevent plantar fasciitis if it hasn't really happened yet, or will I need custom orthotics for this?