Social Media Marketing

Branding - as a corporate entity or as an individual using profiles on social media sites, by blogging, by posting attractive content, and by participating in conversations.

Customer-Driven Promotion - allowing your customers to associate themselves with you and promote you

Conversation and Interaction with Customers - connecting directly and conversing with your customers, users and prospects using blogs, forums, twitter, etc. This might be initiated by you, or you might go to where the conversations are already happening and join in.

Direct Advertising - placing links to your online properties or products where your prospects will see them. This might mean buying advertising on a site like Facebook, or it might mean posting to Twitter when you update your blog with a new posting.

Social bookmarking (Delicious, etc)
These sites let you record web pages of interest (similar to a bookmark or favorite in your browser) and make them public so other people can see them. You can bookmark your own pages as well as others, and they will appear so that other people can click on them and visit them.

Story Submission (Digg, Propeller, Stumbleupon etc)
Here the idea is to invite other people to come read an interesting page, rather than tagging it principally for your own interest. People can vote on the submitted story (up and down) and if it gets enough votes it will appear on the popular and upcoming pages, or in the case of stumbleupon, "stumblers' will be sent to visit it.

Content-sharing (video at Youtube, Google Video, Vimeo etc, PDFs at Scribd and FreeIQ, photos at Flickr, audio to podcast directories)
With these sites you upload interesting content that other people can see or read (video, audio, text) and you can also provide a link which people can click to visit your site.

Collaborative Research (Yahoo Answers, Wikianswers, eHow, Wondir etc)
People ask questions, other people provide answers - along with links to resources, which can include your own site.

Conversations (Twitter, Plurk, Friendfeed, forums, etc )
Post short messages and read short messages from others - messages can contain links to sites you want others to visit.

Blogging
Publish your own content and invite others to comment on it, plus visit other blogs and comment on their posts with a link to your site.

Social Networking sites where you establish a presence (Facebook, Myspace, LinkedIn, etc)
These sites provide you with a kind of "home base" where you can publish details about yourself, and content, and carry on conversations. They also provide groups for people with common interests where you can make contacts.

Alternative online worlds and multiplayer games (Second Life, etc)
Many alternative worlds await your participation (warning - can be addictive!). Some encourage commerce, others don't.

Niche vs General sites

Some social media sites are completely general in the subject matter they cover, and others focus on particular niche topics and subjects. It's important to pick your target sites so that the subject matter matches your own focus.

Do
Help others
Don't make everything about you, make it about providing value to others - answering questions, posting useful content of your own, and providing links to content from other people.

Connect
Make real personal connections with others in your niche.

Position
Put yourself in front of your prospects and customers and provide value - let them see you as an expert.

Use Video
This is the exploding area of social media and it's not hard to do. See my other lenses on Youtube and Camtasia.

Target
Connect with and provide value to the people who need what you have, or that you need, not the entire world.

Track results
Use analytics on your sites to see what effect your social media campaign is having.

Don't

Spam
Making a connection is no use if all you then do is send ads.

Over-promote
Make sure you provide more valuable content and links to others than you do self-serving messages.

Game the system
Creating multiple accounts to push up your vote count or posting and answering your own questions will get found out sooner or later and you'll lose your hard work.

Over-Control
Once your messages are "out there" they are beyond your control. Watch what happens, listen to the feedback.

Expect instant results
This is a long-term strategy.