I hope I don't sound negative, but I'll be blunt. Write about something that you know!
I'll admit I'm still working on writing my first e-book but have tons of experience as an online researcher. All too often people are ready to jump on the ebook bandwagon using PLR content or ebooks that have resell/master resell rights. I don't know your personal situation, however, I do know what I see.
You have come on the forums asking for help on markeing your ebook. The irony is that your ebook itself is about online marketing. This is not the first time I've seen people try to sell an ebook about online marketing yet they are asking how to market online.
Take TrafficMystic's advice. Use your own advice from your ebook. Keyword marketing is also very helpful. Don't worry about Google Ads and so on. Don't worry about PPC. I personally prefer organic/natural traffic. It has worked well for me in the past (and still is working) on non-commercial websites I have done.
There's a company called SBI (Site Build It). They sell a package for about $399/year. Includes one year hosting, domain, step-by-step info on keywords/natural traffic, and has a great online forum. It's aimed at the average user, advanced user, or even someone that hardly knows anything about the Internet.
The guy that created it, Ken Evoy, also has some free e-books on onlne marketing, affiliate marketing. I'm not talking about 20+ page crappy ebooks. I'm talking about 80-100+ page ebooks. Lots of great content. A few years back I tried out SBI and is where I learned the CTPM (Content > Traffic > Presell > Monetize) concept.
On my website I have the seven ebooks available for download for free. I'll admit firsthand that if you purchase anything through the links in the ebooks it does have my affiliate ID in there. However, if you read, study, and apply what's in the ebooks then you can do everything without having to spend a penny on the SBI service. The SBI service is simply what I call an all-in-one package with support.
The link is:
You can also just go to knownothing.net and it's under the downloads section. You do have to register (free) to download the ebooks. Helps in curbing leaching. No worries about commercialism. My knownothing.net site is a completley free, no advertisements, no sale website. The focus of my website is on consumer advocacy and combating scams.