I don't want to cause offence to anyone who has previously posted, but:
you can't pluck a number out of the sky and say "you must use x types of marketing". Every business is different. What works for one business may not necessarily work for another.
The most important thing is that you test your marketing thoroughly. One piece of marketing that leads to 20 conversions, could be better than 20 pieces of marketing leading to 20 conversions, for example.
More is not necessarily better, especially if they are not effective.
Another thing is the cost of marketing - you can't just say "free marketing is best" or "paid marketing is best" - as I said, it depends on your business.
There are many great free marketing techniques, such as press releases! which, by the way, will probably work a lot better than an advert in the very same news paper (due to the trust factor of someone else writing it).
The same goes for paid marketing; PPC is extremely cost effective if implemented properly, and longer term forms of marketing such as SEO/SEM.
But as I said, you will never know what is most effective for your business unless you continually test and tweak!
Cheers,