First: Start with Award Nominations:
This is the obvious one - there are a LOT of SciFi/Fantasy Award Nominations - there are the Hugo Awards, the Nebula Awards, the Locus Awards, the World Fantasy Awards, etc. etc. Since most of these awards are awarded based upon different voters (some are Jury awards, some are voter awards, etc.), they tend to include sometimes some very different books on their lists - though obviously there will be some duplicates.
No one is going to say you'll like all of the nominees on these award lists - for example this year I didn't love and wouldn't recommend two of the Hugo Nominees and two of the Nebula Nominees - but in general you're very likely to find some pretty damn good books on these lists.
Second: Find Authors/Sites Who Highlight Books and give Platforms for Authors to Explain Their Ideas:
The internet is a great place to find book recommendations, and there are a lot of sites that will post them (Duh, you're on this site and I just made some in the last post). And not just reviews - there are many places on the net for instance that will allow authors (and publishers for instance) to showcase their upcoming novels and their ideas.
For example, John Scalzi's blog, Whatever, has a series of posts called "The Big Idea," in which Authors of recent books write blog posts for his site about their Big Idea that led them to their most recent book. Similarly Mary Robinette Kowal does a similar thing on her blog with a series called "My Favorite Bit," where authors talk about their favorite bits from these novels. I love these posts as they often lead me to authors I know nothing about whose ideas interest me - sometimes I find new favorites this way in fact. Of course some of these books I find in this way don't work for me, but that's going to be the case with any source.
Similarly, there are many other SF/F websites out there that publish book reviews and suggestions. I know Tor, one of the bigger SF/F publishing companies/imprints, has its own Tor.com blog where it will issue reviews and previews of upcoming books, even those coming out from other publishers. Similarly, Barnes & Noble's website features a SF/F blog which similarly contains previews and reviews that will link you to books you may not have known about. I could go on and on with blogs, but they are out there, and easy to find, and great sources for finding upcoming books to check out.
Third: Find Authors You Like and Follow them on Twitter and their Blogs to See What they Recommend:
This is arguably the most important part of this list: once you find authors you like, the easiest way to find authors of similar quality, if not similar style, is to see who those authors recommend! Most authors maintain a twitter account, if not a blog in itself, and often they will recommend or pipe up other books they've read which they really like.
This is one of the biggest sources for me to find new books - from reading Ken Liu and enjoying his work, I found his blog, which recommended Max Gladstone's Craft Sequence and Kate Elliott's Black Wolves and I loved both of those authors, so I then looked at who they recommended. Following NK Jemisin pointed me at Martha Wells and her Raksura books for another example. At one point, I read something like 8 books in a row blurbed by one author (Gladstone) and then four books in a row blurbed by another (Kate Elliott). These recommendations are very likely not going to be in the same style of the author making them - authors do enjoy styles and things that are different than their own of course - but authors you like will tend to have similar tastes to you.
I cannot stress enough how great a source of books this is - and the best part is that it chains - one author leads you to another who leads you to another who leads you to another who......you get the point.
One note that should be obvious: DO NOT PESTER AUTHORS ON SOCIAL MEDIA FOR RECOMMENDATIONS (or anything really!). Some authors will use their online personas for pure fun, others for work, others for a combination thereof. Some of them won't recommend anything at all, or if they do will do so sparingly. There are enough authors out there who are recommending things that you shouldn't need to bug the ones who won't - and of course, it's just plain RUDE.
Fourth: Social Media is still your Friend in this regard.
This of course only works if you have some # of followers, so it won't be applicable to everyone, but if you talk about the books you enjoy on twitter, people who follow you might suggest similar or other books to try. I find this more hit and miss than the above strategies, but well...it's another reason to share what books YOU enjoy on twitter/social-media - it'll help others and they'll likely help you back.
And that's about it. Enjoy your reading!