Congrats on completing your work & getting it out to the public.
The first steps would be to revisit your cover design and edit, edit, edit. This is your product and it has to be the best. No amount of marketing can fix that. Customers still gravitate towards a nice cover. And please make sure it looks appealing online, not just the hard copy. For editing- if you can’t afford an editor, look for some writing forums where writers critique each other’s work.
Leverage Amazon, make sure you are in the correct categories; you have the proper quotes, etc…
Some Marketing tips:
To stay low budget w/easy entry, you need to use some form of social media that you are comfortable with and where your readers congregate. I would even create a website where you can exchange ideas and create an email list of your followers.
Contact every blogger in your niche and talk to them. Just don’t ask to send your book. Offer them something as well.
Contact Amazon about paid promotion.
I hope this helps a bit and gets your marketing wheels turning.