This is the single most important rule. Read it carefully. To be a great salesperson you have to care about the problems you are solving. The best salespeople I know put themselves in the other person's shoes or go out of their way to experience the problem firsthand. That's how you really take an interest in solving that problem. When you really mean it, people on the other side can tell and will trust you to help them. Actively listen, ask questions and really dig in.
Love what you sell.
As a salesperson, you are an educator. It is hard to educate somebody and be really compelling unless you love what you are offering. Do you use your product? Are you passionate about your company? If you don’t like what you are selling or aren’t passionate about it, quit and go find something else.
Pick up the phone.
Cold calling, cold emailing or meeting people at a networking event are all hard things to do for most of us. It is difficult to put yourself out there, to meet people and strike up a conversation. Most people worry that they will immediately come off as a "salesperson", which just scares others away. Be yourself, just a regular person who wants to learn. Remember the first rule and being genuinely interested, it works for meeting new people. Be interested in people, focus on listening and really caring. You will be surprised how many great people you will meet and some of those people may even buy what you're selling.
Understand that your product isn't always best
This is a hard one for most people to believe, but sometimes your product isn't the right solution. If it isn't, then don't push for a sale. If your product solves their problem, then so be it and push hard for the sale. If it isn't then help them find the right solution even if it is a direct competitor. You will always win out long-term. Plus, there is no benefit to selling somebody something they don't need. You will end up with unhappy customers and a bad reputation. It isn't worth it.