This one goes hand-in-hand with "Handling Uncertainty." Freelancing can cause a lot of anxiety. Try not to freak out. Remember that the people you contact are people too and also have busy lives and active spam filters.

1. Give people time to respond to you but always follow up. Chances are your contact just needs to be reminded with a friendly follow-up email.
2. Have a backup plan. When I started writing, I applied to a few platforms, like Demand Media Studios, where you pick subjects you know about and write on them. DMS then feeds this content to national newspapers and other online platforms with your byline. Despite not paying much, this process is fairly easy and pays on a continuous basis, so you set your own schedule and earning power. (You can also move up through the ranks.) I still rely on DMS in a pinch. (There are also less successful options, learn to weed these ones out.)
3. Be confident! It sounds simple enough but confidence is huge if you're self-employed. Try not to let on how anxious you might be about something. Sometimes there will be meet-and-greets that are great sources for networking--don't miss out on these! Most things you can learn from asking others or seeking out helpful resources. Don't be wishy-wishy about pay; learn to negotiate and set your standards high. You're worth more than you think, and some clients will jump at any opportunity to shortchange you! (At the same time, there are hundreds-maybe even thousands-of people out there just like you, so you need to prove yourself.)

4. As with anything, NETWORK, NETWORK, NETWORK.