Even if you have the best company selling the best product, it takes self-promotion to make others aware of your business venture. You can't expect to sell your wares without some effort, as no one is going to sell them for you. Big banner ads and radio interviews are in the past. These days you have to use the internet, not just as a platform but as a network.
Your friends are an excellent place to start. Word of mouth is the easiest way to get your name out there, and your friends likely support you and want to see you do well. Don't overburden them, but when you are running a promotion or have a particular sale or giveaway to advertise, ask them to share the news with their networks. Whether they tell their entire Facebook page or a few friends, you never know who will tell the next person and which people will be interested in your ideas.
The key is to get people excited about what you are doing. Your friends will be great sellers, because they will speak about your personality traits as well as your business ideas to people they know and trust -- people you wouldn't have been able to contact in such a specific way otherwise.
Apart from your friends, you'll have acquaintances on Facebook, Twitter and other social media sites. Some of these people know you and some don't. When you start your promotion, make yourself pages on all important networks. Post news articles relevant to your business or product, in addition to original content that you think would appeal to people interested in what you'll be selling.
Don't sell it immediately, and don't sell it all the time. You want people and potential customers to visit your pages frequently. You want them to like you. You want to give them more than what obviously makes you money. They can sense bottom-liners from a mile away. Promote yourself with special deals and discounts for followers of certain media. Make sure not all of your content is pushing something. Give visitors a well-rounded experience, so they want to read about your wares when you do push.
Hold giveaways and online events so people already in your social network will be interested in gaining you new followers for a chance to win free merchandise. Make the rules as simple as possible. Followers can gain more entries by recruiting more followers or advertising the event on their pages. New followers can gain an entry for each page they like. Give out surprise gifts without any strings.
For instance, when your page hits 5,000 followers, give something away to one of them chosen at random, and let people know what you did. "Hey, we've reached 5,000 followers and as a token of our appreciation we've chosen one at random to win!" This will keep people on your page and nourish good faith and joviality. You want your name to be thought of fondly.
Business cards are the most traditional example of self-promotion, and they still get the job done. Make up a few different prototypes of business cards, and have copies of each kind on hand. You'll want a straightforward card for possible investors who seem more conservative and traditional in their tastes. You'll need a modern, upbeat card for buyers who are looking for a service they could possibly find elsewhere. Have a third set of cards ready for when you are running special deals, events and giveaways. These cards will focus on your online presence and create a larger social network for your business.
Be prepared to give these cards to everyone you meet. Don't push your product when doing so. Just introduce yourself, have a conversation and give the card as an afterthought.