Of course you must keep it professional email list, but do not make the mistake of writing without personality. You have unique traits that need to be expressed. Never forget, you are marketing to real people with real problems and real emotions. You MUST come across as a person who has these traits also. (29) Conversions are the ultimate goal for every promotion you send out to your prospects.
I know a marketer who has 135k people on his email list and who earns under 100k a year online. I also know a marketer who earned 435k one year from a list of 12k. You must be willing to track everything you do online. You track, see what's working and then tweak until you get the most bang for your buck without sending any more money.
Tweak your sales copy, tweak your subject lines, your headlines, your ad copy, your call to action. Tweak everything until you get the highest possible return from your promotions. When you get the highest possible conversions from a system you implement, you will earn a greater income without spending any extra cash. It just makes marketing sense, doesn't it? (30) Test the guru. Always be ready to test what the gurus tell you to be true. You must test everything before you can accept it as true.