Do not overwhelm them initially with sales pitches. This is impolite and would drive them away eventually. Build your credibility by giving sound advice on your chosen niche market and offer a helping hand to those who would ask for youar help. By doing these, you will also build a reputation as an expert in your field.
After all, internet marketing is all about credibility. If you have online credibility, your list will respond positively to your promotional emails, newsletters and other online marketing materials. Converting these leads into sales will take time. Keep in mind that not all of these leads are of any value to your marketing campaign.
You must constantly update your list by adding new contacts and at the same time trimming it down with those who do not respond to your marketing materials. You can make a separate list with your cold list and your warm leads. Do rigorous follow up on your warm leads to convert them into sales.
If you can do it, once they've decided to buy your online products, thank them by sending a personal thank you e-mail commending them for their wise choice instead of sending an auto-generated one. This will give a personal touch to your email marketing campaign which most email marketers seldom do.
Your relationship does not end after you got their credit card numbers. You can also check on them and see if your product really delivered what you promised them to deliver. This is another way of online product evaluation. You can get direct feedback form people who actually used your products and plan your next course of action based on it.
You can also provide a questionnaire or a checklist for your evaluation. This way it would be easy for them to just check the most applicable statement on your product than writing an entire essay about it. Follow ups made after a sale will also make it easier for you to market your next product.
You can also give them additional freebies should they decide to purchase your next product as a bonus and expression of gratitude. This is email marketing - at its very best. You get down to the very personal level. You are actually building relationships and nurture bonds between your customers. Continue to come up with useful products of excellent quality and they will always respond positively to your email marketing campaign.