Owner of Word Revolution, a strategy & communication agency for churches and Christian ministries.
The list would depend on your business, audience and overall problem you are solving. Many people focus on the tools, then create process around them and only after that do they pursue an audience.
This equation per se is wrong. The "secret sauce" if you want to call it that way is in your ability to start from the people, then create process of engagement and only then look for tools that allow you to execute your processes.
People > Process > Tools
This is the key. Anyone that start with the tools will be giving you the wrong information. Twitter may be a multi million opportunity for some and a complete failure for others. Radio may be the way some people are successful and that may be completely wrong for my audience.
Marketing is a form a communication and the basics of communication is that there is a message and a receiver. If you neglect the receiver your marketing will fail.
Facebook is a tool that changes constantly but one that, if used correctly, can be leveraged to achieve great success and revenue. It gives you the ability to start with a low budget and build from there.
That being said, the time, effort and money (plus opportunity cost) you spend trying to figure it out will grow.
One of the resources I found to be the most valuable one if you have the time to learn and test things out was through Amy Porterfield (amyporterfield.com). Even her podcast and blog is amazing and her Facebook and Link Building courses are worth every cent.