The greatest challenge in e-commerce is the marketing process.
You need to make your website or product page become well-known to everyone and to increase sales.
How to get new customers or at least keep your existing customers to buy more from you?

Getting your website at the top ranking of the search engines is a good way to welcome new customers.
How to please and keep your existing customers to keep buying more from you?

Strategy 1
Learn from your competitors:

Buy your competitors' products and stay up-to-date with their sales process. Buy their products and see what happens after that. Keep a log of what they do after you buy their products. Do you get any email from them? If so, when? Did you get any phone call from them? What was it about? Most likely they wanted to sell more products to you.
Most e-book sellers will continue to email you for their latest updates on their latest products and offers!
Learn from your competitors, that's it!

Business is as usual on or off the net. What make online business unique is the ability to minimize labour cost and maximize performance..

For me in 'online business training' which specialize in providing courses to train people to do their own business online, rapport building is very vital..Although your customer may reach hundreds at a time, but the ability to use your sistem to approach them personally is awesome! At the same time, they will feel being empowered through series of publications aiming each customer personally.

They wil buy and buy and buy or if subscription service, they will keep on subscribe.

Your 'strategy 1' can be used if you are still looking for niche services/products. Once your business is running, it will all about your customer and personal approach is one of marketing aspect