I built an app for sharing useful advice/tips/perspective (like a cross between wikihow and instagram), now I need to beef up the content and user base. Is it easy/possible to piggyback off current users' email contact lists or Facebook friends, etc?
Can I rely on networking and word-of-mouth, or will I need to raise money for a marketing budget?
This will all depend what you are looking for: testing for data, growth channels, distribution channels. A bit more information needs to be provided.
There's no secret sauce for going viral. The best way to create a strong foundation for an app is to have a demographic own it.
This loyalty will provide structure and allow you to expand, but first, you must enhance. Enhancing is focusing on a small group and providing tremendous value.
don't expand without enhancing.
Enhance, then expand.
Always look for the free avenues first before putting down any dollars as you are running lean as it is. Look to on-line forums, groups in your target market that are discussing the subject area and begin engaging and sharing insights to show credibility for your offering. As you move forward, begin to request advice in developing the basic product offering. You can then start providing incentives like entries into a draw to this focused target market, as opposed to general contact lists that get very little conversions (unless it is a targeted e-mail list). This should get you started.