It's worth underlining that it's only a perspective from an internet marketing viewpoint - I wouldn't be surprised if Mark Robson has a different take on it from a publishing business point of view.
It's also worth pointing out that it's only a general overview - there's loads of avenues you could go with via SEO and advertising - I simply haven't been able to detail them all here.
As for PPC - I've seen some self-published authors really push on this. They often say something like "If you like XXX, then you'll enjoy XXX by XXX". However, whether they actually get much of a return on investment is another matter.
If it's any consolation, the PPC rate for SFF topics is pretty low - that's good for advertisers, but not so good for publishers.
The main thing I really wanted to get across is that simply joining online groups to advertise a new book or writing project is absolutely the wrong way to go about it. It's spamming, and it's badly received.