Unless you're used to doing cold phone calls, and fairly adept at reversing a prospects objections - I would first start with Linkedin. Emails and phone calls

Unless you're used to doing cold phone calls, and fairly adept at reversing a prospects objections - I would first start with Linkedin. Emails and phone calls are easy to ignore. I would first use LinkedIn to approach them asking for advice (keep the intro short, sweet, but intriguing). Then email a few times via LinkedIn - and THEN ask for a phone call. If you do decide on phone calls, I would first find another group of 20 people you don't care as much about their answers- and use them first to "refine your approach" and reduce nerves.