If you like their books, say so! Like, on social media and stuff. For example: TINSEL RAIN is coming out Friday. If you’re a Kickstarter backer, and you liked the book, there is almost nothing better you can do for me right now than say so on as many of your favorite social media platforms as you care to post to. With the link (https://www.amazon.com/Tinsel-Rain-Tom-Vargas-Mystery-ebook/dp/B0B243FV1N), and a picture of the book, if you can swing it.
And here’s the thing: if you don’t like my book, you can still do this with books that you do like. It is a very rare author indeed who will object to people saying in public how awesome their book is, and what the link is to buy it. So, even if you hate my guts, the advice I’m giving is still good.