You, your marketing messages, email list and your investment (money & time)! And here is why. While most people agree that "client referrals" are one of the most effective and email list efficient methods to develop new business, other "tools" are not quite as clear-cut, because it really depends on how you use them. Take networking for instance email list. Again, most people report that networking has been a highly effective and quite efficient business development tool for them.
But imagine what would happen if you email list were a lousy networker who made all the typical networking mistakes under the sun. Do you think networking would be an effective marketing tool for you? Or take cold-calling. People who do it properly see email list it as an effective tool for business development. Those who email list don't do it properly typically pooh-pooh it and consider it an anachronism or a waste of time and resources. But think about it! Of course email list, cold calling will never work for you if.
you are horrified at the sheer email list thought of even picking up the phone you don't say the right things when someone answers the phone you don't invest enough time to make enough calls you waste too much time calling the wrong people. Or, if you can't deliver a decent speech email list or presentation in front of a group of people, even if your life depended on it, don't do it! Presentations and public speaking engagements won't work for you.