RE: I Have Submitted Manuscripts to Four Publishers Now. Anxiously Waiting on a Reply.
Good luck. You're a very talented writer and you'll get an audience.
Have you come across Mark Dawson's self-publishing course:
I did the 101 course and it was exceptionally good and I don't often praise things. It goes through the mechanics of making a living from your writing. Everything from the front & back matter (things like a link to a landing page), to building a simple website to collect emails, to getting readers and signups through giveaway & promotional websites. Then the automated emails you ought to keep in constant contact with readers, then asking for reviews and then how to get on to promotional sites i.e. Bookbub etc. where you can get massive exposure and megabucks.
He's got a later course which focuses on ads to promote back catalogues of books. As you have a lot of work already, it could be very useful.
Mark himself is on target to earn over $1 million this year from his thrillers on Amazon. And there are lots of beginner writers in the Facebook group who are doing incredibly well.
As for myself I did the 101 course, released a novella, got ~100 email signups in 2 weeks and have some promotions running next week.
It's still early days for me, but you'll do much better much sooner, as you have lots of material to work with. In fact I did the course in one month, then cancelled and didn't actually pay anything for it, I got a refund.
At the very least it's worth signing up to his emails and podcast.
Also re: promotion of your old books, look at this link below. This guy has spent over $30k on promotions in several years and knows what works, and what doesn't.
Anyway, good luck and feel free to drop me a line: alexclifford93 at gmail