I would say a certain level of deception is your greatest tool in making money with marketing...hope this helps
marketing as all about 2 things 1. Getting people to respond to your ads 2. Getting people to see your ads thats the basics now begin to study those 2 simple but complex ideas and then you can make money online. It is not easy though it takes work and lots of research if it was easy every idiot on the planet would do it
i find marketing with postcards as one of the most effective way in promoting your business. It is cost-effective and can be easily produced and distribute to your target market.
articles, Digg, StumbleUpon, social bookmarking, PayPerClick, search engine optimisation, Yahoo Answers, forums, blog comments, Twitter, Facebook..... There are so many different ways - you really asked a very open ended question. Basically, try them all, see what works and repeat
Web 2.0 is the best way to do the marketing but with that you wont be able to get steady traffic. So have original contents and start quality and relevant link building for that.
and what your goals are. IE Do you want steady long term growth in results or a short sharp hit (White hat vs Grey/Black) ..and what your budget is. If you have funds available and are confident about your return on investment then try some PPC, then use the learnings from the PPC stats to build your SEO campaign. This assumes your marketing campaign is digital, and of course SS101 is right; If you are selling home made cup-cakes - ignore my reply...
Now days social media sites are playing a very important role in marketing . Sites like facebook ,twitter , eZdia , orkut , etc are important for this. To promote a business many are using these sites. It not only helps to promote the business but also helps to grow your network which is also an indirect way of promoting your product. Also there is no investment in this thus it is free and effective
article marketing is another better for generating more traffics if there more traffics then obviously there will be more revenue.
It would highly depend on the market you are targeting. Also, your best answer would probably be "All of the above" because there are numerous tactics that can get your lots of traffic, some markets will respond better to different things, but most of the time a combination of several things will work best.
Search engines have worked best for me, but just because it works best for me does not make it the best.
Marketing online is a broad stuff and there many useful marketing methods that makes it difficult to say one is better than the other. However, SEO, article marketing, blogging, Social bookmarking, PPC are very important. There are still many more.