Thanks for moving to the appropriate sub-forum...and many thanks to those who have replied
I did read through much of the SEO Dweeb thread, and found it useful but for the most part doesn't cover various paid services and other advertising/review options that are available online. It's more about appropriate self-promotion through social media, forums and communities rather than direct advertising/promo (which is what I'm interested in here). Definitely important and some really great advice in that thread which I'll be looking to implement (it's also reassuring to know that I'm doing a lot of it already and have seen some success), but not really what I was asking about. Just saying.
There is of course plenty of material on here for me to dig through, and I'll certainly be focusing on doing that, but I thought people like the thought exercise of divvying up $500 specifically and seeing how it might be rationed out (particularly given that the coveted Bookbub is sometimes a difficult nut to crack). I was also interested in getting up to date information, as these things move very quickly in the digital sphere and many of these threads are a few years old at this point...
I haven't seen much success from either Goodreads or Amazon advertising, and certainly not enough to cover the cost of the marketing. So will be looking beyond those for some next steps. As this is my first novel I'm willing to throw more at it (removing any expectation of profit really!) so that I can learn some needed lessons for any future work. I'll be taking a close look at this over a planned long-weekend and will report back with my own decisions on where to spend the money...
If anybody else has any good suggestions or services/channels they've had success with please do chip in! Facebook advertising is something that I had kind of written off, but have seen enough people recommend it now to give it a (small) shot. Then of course the Countdown Deals combined with the various listings that people recommend, if I can get approved.
I'm excited to see what comes out of it, and will definitely share any experiences/success/failures with you all