In case it helps you decide whether to go with a publisher or self-publish, I wrote down some thoughts about the self-publishing avenue: https://medium.com/@robaboukhalil/how-i-wrote-a-technical-bo... :)
With me, plugging the book at conferences. Trying to get people I know who read it to put reviews on Amazon. (In my experience, lots more people say they will than actually do it.) I was able to arrange a book signing at one event. Email list/newsletter if you have one. Social media. Website/blog. Etc.