I had to do this as a business intelligence journalist in Turkey, having come to the job from an editorial background. There was quite a learning curve from sitting behind a screen to having to speak to actual people. As I've sat here, distracted with answering your question, I've drafted this copy three times, because I found there is a lot I actually have to say as a result of my experience here (which was initially terrifying). I'll stick to the phone calls though...

First, calls are not networking, and networking isn't making friends. It's possible that you can sit down with a percentage of your network and share a beer, but I imagine you won't be turning these people into your board gaming buddies – besides, that's not the point. You are calling/meeting folks under the pretext of exchanging goods/services, so don't confuse this with an opportunity to 'just be yourself'. Some have suggested acting, to that I would add a few specific tips.

The real trick is preparation. That means, knowing who you want to speak to and what you want to say. If you are calling, have it written down in front of you to refer to when you are learning.

I worked out a flow chart on paper with boxes for the things I knew and the things I didn't, so I could pitch the right people and ensure I both conveyed and received the information I needed to follow up. I would fill out part of the chart while doing my pre-call research on the company/person. It included boxes for a lot of contingencies:
receptionist's name
assistant's name/email
CEO's name/email (our target's were always CEOs)
CEO's availability – Can I schedule the meeting now?
follow up via email – Do I have the email/phone number of the CEO?
Good time to call back – Is s/he available after 5PM?
CEO's mobile number?
CEO's travel details/conferences s/he is attending?

I noticed a trend with my calls that everyone would ask if I could send an email, so, I took to preempting the request by doing a 15-30 second introduction about the publication I worked for and telling them I wanted to send an email with more detail. Every one of those seconds is important, so practice speaking clearly and on message, don't waste time with adjectives or a grocery list of facts about your company/service – explain who you are, why you called, what you hope to accomplish, and end with why it's relevant to them.

In my case, I usually referred to a previously published comment from the person, or referenced another CEO in the industry who gave us a meeting and explained that we would like their comments as well to balance our coverage. If you are selling a good/service, knowing their problem and how your service solves it is probably a good idea. The thing is though, the CEO might not be aware that the problem is THEIR problem.

So, alternatively, if you can cite a competitor of theirs who is a customer of yours, and share some results they gained from your product, that would help the CEO do the math for why they might want your goods.

I also learned that on a given cold call, I would likely hit the HQ receptionist (or the CEO/GM's secretary) and then get transferred to their assistant. Initially, I wasted time trying to explain myself (in not my native language) to a receptionist who could care less, so the first thing I changed was to stop asking for the CEO by name. Instead, I would quickly introduce myself and company name, then ask for the CEO's assistant. In Turkey, the assistant is the gatekeeper anyway, so on a cold call I was going to be referred to him/her. It was best to prepare to pitch them as well, in the same manner I described above.

Most of the time, this worked, but it was very rare that I could schedule a meeting during the cold call. So, following up is important as well. In doing so, linking to the information you cite in the call got me a lot of results, but as was indicated, it is something of a numbers game, so being discerning about who you call is the best way to improve your success ratio.

This worked for me, having never previously made a work-related phone call, and I scored meetings with roughly 300 CEOs and government ministers. I learn by doing and making mistakes, so I wasted a lot of time tripping over myself. Hopefully, these tips will at least save you some false starts. Good luck.