As so often happens, one of the greatest decisions I have made in my professional life was also the toughest: becoming an entrepreneur. Letting go of the security and luxury of an executive position to start my own startup was not an easy call. Certain financial aspects became painfully clear, and I found myself making calculations I would have never even considered back in my "all expenses paid" days.

Following a short period of time as a consultant I co-founded mobile-marketing agency Moburst, and the best decision of my life has recently celebrated its first birthday.

During this crazy year I have come to realize that startup newbies are bombarded with opportunities left and right and face the overwhelming challenge of refusing attractive proposals on their way to success. But learning to say no may be the most important skill to develop on your new adventurous path.

Here are a few instances where saying nope can do wonders.

Related: 5 Things Successful Entrepreneurs Do Differently

1. Say no to doing everything on your own.

A solid partner is so much more than someone whose company you enjoy, or the person who just happened to be there when you first came up with a brilliant idea. Look for someone who shares your vision and goals, and with whom you wouldn't mind working well into the night. It's also important that your partner is somewhat different than you.

My business partner provides a balanced perspective to my fast- moving ways, and often serves as the voice of reason at our company.

2. Say no to working for crumbs.

Much like beginners at any field, young startups tend to think that the connections and experience they'll earn are enough and assume that serving clients for a ridiculously low fee will help spread the word and bring in the deep pockets. In reality, the news will spread that you are willing to work for basically nothing. While it is important to open doors -- make sure you open the right ones. Your brand's reputation is formed from the very first second, so make it a well-respected one. If you believe your product is truly valuable, you should always demand appropriate payment.

Related: The 6 Skills Every Successful Entrepreneur Needs

3. Say no to great potentialemployees.

As strange as it may seem, skills and talent are not enough. Hire those who can relate to your company's core values and goals. It's especially crucial for startups that the team is deeply committed to building something together, so look for employees who take pride in their work and business field.

In our case, we learned the hard way that everyone on our team must be fiercely invested in the mobile world. That is why we inform job applicants that those who are not mobile oriented need not apply.

Another factor in the young company equation is the massive importance of the team-building operation. If your gut tells you that a certain person won't mesh well with the group, don't risk harming the team's fragile dynamics. Put in the necessary hours it takes to build a winning team -- it's the most important form of ROI you'll ever receive.

4. Say no to what makes you uncomfortable.

A few lucrative fields are considered a no-go zone for our company. Refusing to promote clients operating in these fields definitely means losing money but there's something far more important to protect here.

Similarly, we refrain from marketing a product of very low quality, or take part in a project we can't significantly contribute to. What guides us in making these decision is knowing that today's honest refusal could earn us major points later on.

Related: 3 Characteristics Successful Entrepreneurs Never Have