Here's io9 with a panel taking the approach of "entry level" science fiction, which gets rid of some of the problems. One thing this panel makes obvious is that "sf," or as John Clute would say, "fantastika," is a house that contains many mansions. For instance, one panelist wants to get people to read heroic fantasy. I've been reading sf for 60 years, and no one has ever gotten me to read heroic fantasy. Paolo Bacigalupi thinks people will want to read stories about how the world will be even shittier in the near future as long as they're not scared off by that nasty Science Fiction label.
We have recommendations for tales that are full of human interest but go easy on the explanation (The Handmaid's Tale) or have wonderful prose and characterization but How We Got There or How It Works make my crap detector not only ring but set off rockets and smoke bombs ("Aye, and Gomorrah," Never Let Me Go).
I don't want to minimize the problem. A lot of sf is written for people who are familiar with sf, and a lot the older stuff suffers from defects that weren't obvious at the time. N.K. Jemisin recommends Childhood's End, but warns of the racial aspects. Stranger in a Strange Land was a great gateway book in the 60s, but now its acceptance of unexamined assumptions about the roles of the sexes makes it unreadable for many. (And I for one am still grateful for many of the things it taught me in other areas.) With all the difficulties, the panel has some really good suggestions from, among others, John Scalzi and Seanan McGuire, whose own work is recommended by others.
The whole thing reminds me that I am odd, even among science fiction readers. I don't like popular fiction. There, I said it. I do not enjoy suspense and adventure. Pop fiction, like alcohol and sodomy, gets so much moralistic opposition that many of those who enjoy it can't imagine anyone refraining just because they don't find it fun, but that's how I feel. I took up sf because it was Good to Think With--what if they do this? how will it work? what happens next?--and I put up with Story Values to get what I wanted. Perhaps the people who erroneously think they don't like sf should be reassured that it isn't just for people like me.