Ask HN: Need some advice/learning resources on online marketing

I am wondering what approach one should take to plan and execute promotion of their product(s) online. The scenarios I'm interested in are: 1)snowday2011.com like projects where one or two products based on a particular event or hot trend are sold. How to quickly reach the target market, bring in visitors and turn them into customers? 2)Marketing a new brand for clothing line? A clothing line that will start with 10-15 t-shirts based around a particular niche concept. How to determine the target market? I'm looking for not just visitors but customers who will actually buy the product online(not many shop online in country like India) How to reach them online? Where to find them? How to approach them? How to make it viral? How to make my visitors/customers promote my product? How to retain them and make a community of customers?