Here are some habits of the worst sellers. I see these over and over again and looking at these (I'm hoping) will give you some insight on what to avoid. Some sellers make lots of mistakes, here are a few;
1. Thinking you can do it all yourself.
Selling is a a numbers game. It used to be that you could spend your time smiling and dialing but these days calling, integrated with marketing, is a better approach. Cold calls have very low probability by themselves but comblined with good marketing campaigns can be very effective in B2B sales.
2. Talking too much.
Salespeople like to talk. The fact is, the best sellers are great listeners and they use silence really well. Listen when you want your customers to talk more. Silence is appropriate when you are listening so you don't interrupt your customer - ever.
3. Doing the same things in all situations.
One of the predictors of sales success is the ability to think on your feet. Some salespeople start their sales calls the same way and act the same way with every type of customer. It just doesn't work, especially at executive levels.
4. Expecting things to happen now.
Some things just take time. If you want a piece of business badly enough you may have to be persistent and try to make contact over a period of months. Be patient and don't give up if the account is worth it. Salespeople have to be able to deal with ambiguity and the unknown and patience is powerful when it's combined with persistence.
5. Thinking it's easy.
People think selling is easy only because the great salespeople make it look easy. "Easy" really only comes with lots of years of experience doing the right things over and over again and getting the planned (subconsious) results. Until then, prepare!
For another view of this topic read Stephen Schiffmans book, "The 25 Most Common Sales Mistakes: And How to Avoid Them"