Forget five things; I could probably write an entire book about all the successes and failures I've encountered since I opened the doors of my e-mail marketing company, VerticalResponse, in 2001. How we did business back then was vastly different than the way things are now. (For one, this little thing called Facebook didn't even exist!). Customer expectations have changed, and the technology we have available to us is certainly more advanced now.

After 11 amazing years growing my company from four people to now over 110, here are some things I've learned:

1. Nothing's Impossible

Things that might've been unrealistic before might be possible now. Companies are run by different people at different times and your collective skill set will change. For example, I wanted to offer discount codes to our customers for many years but my team at the time just didn't have the background to engineer it. Since then, new people have come on board, along with new technology, and now we've got a promotion code engine!

2. Put Your Thinking Cap On

Every once in a while, do yourself a favor: Stay home and think. Think about what you aren't doing now but want to do in the future. Think about what the competition is doing that you should, too. Think about how your company fits into the grand scheme of things. Think about how to retain existing customers and bring back the ones who've strayed. Sometimes you just need to be in a comfortable surrounding to re-energize your brain. (Just don't use this as an excuse to go to the spa!)

3. Show Your Face

While nothing makes a bigger impression than face-to-face communication, you can't be everywhere all the time. Make the most of one-on-one opportunities with customers, like setting up live webinars, posting videos and blogging regularly to add personality and lend credibility to your business.

4. Try It Again

Simply because a certain strategy failed in the past doesn't mean it won't work today. If you advertised on Google or any other site a year or two ago and didn't get the response you were looking for, now could be the right time to try again. The site may have merged with another company or tapped into some brand-new leads, so consider giving it another shot.

5. Embrace the New

Fifteen years ago, e-mail marketing barely existed and now it's a multi-billion dollar business. Five years ago, the power of social media was largely unknown and now it's turning the marketing world on its ear. To remain competitive, you need to stay up-to-speed on what's out there and take advantage of free, simple tools, like Roost (which my company just acquired), which are rewriting the rules of engagement. Then spend the extra five minutes a day communicating with followers and trust me, it'll pay off.

Even after more than a decade as a business owner, I'm still learning every single day - from my employees, colleagues, competitors and the amazing community here on Inc.

For all the business "veterans" out there, what lessons have you learned over the years to stay in the game?