A successful entrepreneur, Avi Yashchin is a leading voice in clean energy, education, finance, and pioneering technologies, harnessing his expertise in each area to make the world more efficient and sustainable. Avi is the founder and former CEO of CleanEdison, a vocational education company that focuses on clean energy. Follow Avi on Twitter @AviYashchin.

When you quit your job to become an entrepreneur, it can be tempting to adopt a "don't look back" mentality and go out in a blaze of glory.

But if your former colleagues believe in your entrepreneurial vision, they could become your first investors, clients, business partners, employees, and referral sources. In today's startup scene, you need cross-industry skills more and more: tech people can create great food startups, finance experience can help support education startups, etc. So don't burn bridges, even if you're leaving for a different industry. Don't even think about it.

Here are some ways you can leverage previous employment experience to benefit your startup.

1. Start an alumni network.

This network can be a great source for vendor referrals, employee recruitment, and even client acquisition. There are many free platforms (Yammer, Chatter, or a LinkedIn Group) that can be used to build and maintain these communities. Alumni networks also help employees stay in touch so they could easily come back in a few years, with more experience and a fresh perspective. Once you're connected, look for ways you can add value for these people. I've used my employee alumni network to recruit some of our top product managers, HR reps, and top-performing salespeople.

These alumni networks can be a good source of referrals as well. Your former bosses and colleagues already know, hopefully like, and trust your personal brand. This familiarity makes them a perfect reference to provide valuable recommendations when closing important deals. You can also seek out their opinion when creating new products or features for your existing business. It's important to seek feedback early and often--especially from people who will be totally honest with their feedback.

2. Recruit people you know.

Your former colleagues, vendors, business partners, and investors are the perfect place to start your search for talent. These candidates are likely to recommend people of higher quality, and they'll be able to introduce you to candidates who are better adjusted to your work environment. When you recruit from your network, candidates will have more realistic expectations, come into your business more motivated, and hopefully will be a better cultural fit than people from the big job boards.

Hiring from your network can also be a lot less expensive than hiring recruiters, but you will have to buy your recruiting friend a beer or two. One of my company's early employees was someone who I worked with on Wall Street. Historically, many companies have been founded by small groups of people who were battle-tested in Fortune 500 companies, then struck out on their own.

3. Reflect on past experiences to uncover your values.

Your former network isn't the only aspect of your old career that can benefit your business. Simply reflecting on past work experiences can lead to insights that will influence your decisions. Did you have a boss that was particularly belligerent or particularly motivating? Use your experience to guide your own behaviors. Based on my Wall Street experience, I decided that my company's culture would not be exclusively about making money, but also about creating an appealing working environment that includes a flat organizational structure and transparency.

Jobs and companies come and go, but the relationships and experiences you gain along the way can last for a long time. As Maya Angelou once said, "People will forget what you said, people will forget what you did, but people will never forget how you made them feel."

When you work to maintain good relationships with your colleagues, they can help you along your entrepreneurial journey and increase your chances of success.