As your career evolves, you will build a mutually supportive network of people who will support your career in many ways, including providing career advice, specific help, useful introductions, and information about vacancies.
Your network will be more effective when you nourish it. A simple way to do this is to communicate regularly with your network, both in person and online. Put a reminder in your calendar to catch up with those nearby or get in touch via email or phone.
When communicating, remember to listen as well as speak. Both you and your contact will be better positioned to help each other at short notice because of those regular conversations.