Sometimes it can feel awkward networking with others who might be the catalyst for your next career opportunity. There might be a sense you're being opportunistic and just connecting because you need a job. But inviting others to participate in your career search as a resource for information provides you a better sense of an organization, position, market hiring patterns etc. It's also less threatening for the potential information interviewee to know the conversation is information gathering, and less about them as a conduit to your next job.
The more targeted you are in your career search the more precise your conversations will be, and the value of the information will have greater impact for you. Consider "six degrees of separation" as a strategy to identify potential information interviewees, and be prepared to define the goal of the relationship, as well as who you are and what goals you have for the conversation.
There are many sources for building your network of contacts. Your personal network will always be the best way to make an introduction. Additionally, LinkedIn allows you some precision in connecting with professionals employed in functional areas you're interested in. Meetups or professional association meetings provide you the optimal opportunity to meet your future information source face to face, which in many ways engenders greater connection and trust. Always be prepared with a complete resume, as well as the questions you're curious about, as many potential information interviewees are also potential employers.
In conclusion, there are many avenues to express your resourcefulness in identifying the right information interviewee. Keep in mind another advantage to this strategy is many jobs are never advertised. Informational interviews are an excellent way to discover that hidden job market. Do your research and be focused on the position, organization, and function you're targeting. Have your questions prepared and ready. Do keep the questions in each conversation to 3-5, and be mindful of the other person's time. Information interviewing is a high contact sport, so be ready to engage and build rapport.