When you're starting a business — or even just thinking about it — the advice you'll get again and again is to find a mentor.

But here's what's more important: finding the right mentor.

The mentor-mentee relationship is a lot like dating. You must share mutual interests, really want to spend time together and be equally committed. It takes time to identify the perfect fit, and to be honest, sometimes there's not a match. There are also fundamental qualities in your mentor that will determine whether you'll get the most from the relationship.

While running my own business, I've been fortunate to have several excellent mentor relationships. Looking back, here are the three things that I've seen really ensure success:

1. Chemistry

The most important thing to find in a mentor is chemistry. There has to be a fit between the two of you if the relationship is going to work.

What does this mean, exactly? First, there should be at least one major interest that the two of you share. What's more, though, it's important that your mentor shares some of the same ideas and views that you do on that topic.

If, for example, your business mentor is a sales expert and a firm believer that the customer is always right, but you believe that focusing on customer support is a waste of time, it's unlikely the two of you will have a lasting relationship. Even if you don't know what your beliefs are on a particular topic right away, getting to know your mentor's views on issues you believe are important will be key to finding the right one.

2. Commitment

When I think about the best mentors I've had, it always came down to commitment — or how much time they were willing to spend with me. Because successful people are usually good at what they do, their time is in constant demand. But if a mentor is willing to carve out even a small slice of his or her day to chat with you, that can make all the difference. It shows their commitment and helps you gain a lot out of the relationship. It allows you to really learn and ask questions. And it provides a sense of support should something come up down the road.

One of my mentors today travels a lot. Although his family and home are in Silicon Valley, he travels to Europe once a month, sometimes for a few weeks at a time, to meet with his team. Despite his hectic schedule, though, he always makes time to speak with me, even if we have to do a quick Skype call at the crack of dawn. For me, that sends a message that he is willing to put in the time even if he's on a different continent. And that's exactly what you want.

3. Honesty

Yeah, yeah, it sounds cheesy and weird, but it's true: Honesty and integrity are important in a business mentor.

Maybe it seems obvious, but what I'm really saying here is that you don't want a mentor who is going to tell you what you want to hear just to make you feel good. If you are going to get any real learning out of a mentorship, you need to have someone who will be honest with you and let you know when you're moving in the wrong direction. Constant flattery and sugar coating will not help you learn.

This may also mean you need to build thicker skin to take the criticism, but if it's done correctly, the result will not only be constructive, but eye-opening. One of my mentors, for example, is great at calling me out and being brutally honest, even when I disagree. Recently, he told me it was time to stop being a founder and start being a CEO. At first I didn't see the difference, but it was actually a great wake-up call — and I needed it.

Read more: Want a Mentor for Your Business? Look for These 3 Qualities