Although money is needed to expand and advance a business, an entrepreneur can significantly contribute to the growth of his or her company by simply investing intangible resources such as time, energy and creativity. In fact, some of the most rewarding investments that I have made in my own business and career required very little, if any, use of monetary resources.

For example, a startup can benefit from its founder attending a free networking event for people in his industry. That act, attending a networking event, in itself is a business investment. He invests time and effort and in return, he gains new contacts, future affiliates and possible partners. Likewise, an entrepreneur can create new leads by simply writing and publishing an useful article in the local newspaper.

Below are four important investments that every entrepreneur should make.

1. Increasing knowledge.

As an old adage puts it, "the best investment you can ever make is an investment in yourself".

Great entrepreneurs invest and continue to invest in their knowledge base. Legendary investor Warren Buffett reads five to six hours a day. Mark Zuckerberg took Mandarin (Chinese) lessons and now uses the language to expand his business in China, the largest economy in the world. His Mandarin caught the attention of many in China, allowing him to promote his name and his brand to a big market.

Businessmen like Buffett and Zuckerberg understand that enhancing and growing their skills and abilities is critical to the survival of their business.

The beauty about learning is that it can happen in so many ways. You can learn by reading books, watching documentaries and listening to podcasts. You can also do it by going back to school. Interviewing successful individuals and being mentored by them also helps as they can give you insights from their experience.

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2. Building a Rolodex.

Sometimes the connections you have are worth much more than money. An entrepreneur with a powerful Rolodex has access to influential people in media, potential investors, high-quality talent and business partners.

Networking events are a great way to build your Rolodex. In addition to increasing the number of people you know, they can improve your networking and communication skills. This ultimately results in having more referrals for your business, and that is good because business referrals are much cheaper than advertising and they creates more opportunities for repeat business.

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3. Getting known.

It is often said, "If nobody knows you, nobody can do business with you."

Luckily, entrepreneurs today have no excuse to remain in obscurity. Social networking platforms and mobile apps such as Periscope, Facebook, Twitter, LinkedIn and YouTube allow anyone to build a brand at virtually no cost. More importantly they provide entrepreneurs with the ability to sustain and build relationships with old and new clients, while introducing them to new markets.

Agreeing to speak at functions for free is another way to market yourself as an expert and a great way to promote your business to a captive audience. Sharing knowledge and information is a way to establish yourself, and your business. The more you are known, the more people trust you, and thus the more clients you bring in to your business.

While a small business might choose to invest funds into a replenishing its inventory, building a website or purchasing new office space, its owner can make investments just as important without money. Entrepreneurs reap countless benefits from simply finding the time to learn more about their field as well as putting in enough energy to make valuable professional connections and build a reputation.

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