Well I had a false start with my father handing me HG Wells when I was about 12. Read War of the Worlds, then the Time Machine (which was a bit marginal in terms of too scary all those white creatures) then the Island of Dr Moreau gave me nightmares for ages and I couldn't face any more.
Then about 2 years later I happened to borrow Anne McCaffrey's Dragonsong from the library and read it twice before handing it back and had to have my own copy. Most of her Dragon books happened to be out of print in the UK that year, but then they started coming back on the shelves. My local book shop was a small one so I had to order them, but that is where all my pocket money went that year.
I think John Wyndham was probably the next SF author I read. Read The Hobbit at some point but never could get into LOTR - text was too dry. The range of what I read just expanded with the available libraries and budget
I think for me the important things in the fantasy and SF I read are:
I can believe in the characters.
They have a lot more going on in their lives than trouble at school or marriage problems
You meet strange and powerful creatures/aliens
You can do
anything with sf and fantasy settings - your imagination is the limit. I get to be somewhere totally else for a few hours. Also some of the SF additionally look at where the world might be going - in an interesting and ultimately positive way. (Forget apocalypse novels, way too much doom and gloom on the news already
)
So to paraphrase the start of the thread - Infinite Diversity in Infinite Combinations