What do you think are the best and effective internet marketing strategies?

Try these steps, apart from social media; Start with a web promotion plan and an effective web design and development strategy.

Get ranked at the top in major search engines, and practice good Search Optimization Techniques.

Learn to use Email Marketing Effectively.

Dominate your marketing niche with affiliate, reseller, and associate programs.

Request an analysis from an Internet marketing coach or Internet marketing consultant.

Build a responsive opt-in email list.

Publish articles or get listed in news stories.

Write and publish online press releases.

Facilitate and run contests and giveaways via your web site.

Blog and interact with your visitors.

For small businesses I'd say Google SEO and social media.

Hiring an S.E.O and S.M.O are one of the most basic and effective strategy for an Internet Marketing.

The best strategy is dependent on the product and service that is on offer. We will -- always -- have to tailor make the strategy and there cannot be one single avenue to make the best use of internet. 

Thanks for the invite, I agree with the rest of the answers