I got into comics pretty heavily about 5 years ago and have fallen in love with the medium, the power of pictures and words is something that is overlooked by many (including many comic writers). It is an extremely expensive hobby though, so here are some tips to manage that:
Use the library: I first started getting into comics though libraries, they are fantastic and you can get a huge selection. Plus it's a great way to explore the genre, grab a bunch and if you don't like something, no sweat, move on to another book. In Canada (at least where I am in Canada) they separate the adult graphic novels from the all ages stuff, which is great cause some of those adult books can get very sexually explicit and violent. But it's also a way to help you sort for stuff you like, if you want biographies and mature content you have a separate section than the all ages which is where you will find most of your Marvel and DC content (though both have some adult content too)
Bargain bins: Most comic stores will have bargain bins were you can get graphic novels for about $5 or floppies for $.25-$1. Those are a good place to sample new stuff and I have found most of my favorite books in those.
Piracy sites: I won't be specific here cause I don't want to advertise any sites but I do pirate a lot of stuff, especially all the new series from Marvel/DC. Not many have the money to buy every new number 1 from Marvel DC to find the new good series, nor do I think a person should have to buy a book to sample it. There is also the problem that Marvel has been relaunching books once a year, this is a terrible business practice and should NOT be supported. So I usually pirate the first couple issues and if I like it I will buy them.
Marvel Unlimited: This is a good way to get old comics. It's a digital subscription service that allows you to read a TON of the back catalog. I find that the 80s and the early 2000s are two extremely good era's for Marvel and there is lots of good stuff on Marvel Unlimited.
It took me a while to hone in on the types of books I really like and it took a lot of experimenting with new types of books and a lot of just straight up gambling with random books from the bargain bin. But I feel I have a pretty good grasp on what I like now. As for science fiction here are some good ones to start on:
Ocean/Orbiter by Warren Ellis: collects 2 stories, he is known as one of the best comic writers and these two stories are my favorite. Orbiter is an uplifting story of a dystopia that finds it's love for space again
Orbital by Sylvain Runberg: (yes, can get confusing with the above comic) European comic and a bit Star Trekian in it where it's attempting to solve conflicts between species with politics. Not 100% successful cause then there would be no action, a nice blend of action and politics.
Star Trek Broken Mirror: Speaking of Star Trek. Takes place in the Mirror TNG Universe where the Federation Empire has been pushed back to earth. Oddly, Barclay is one of the main characters.
The Metabarons by Jodorworsky: If you want a weird space epic this is the best of the best. It follows a lineage of Metabarons as they become the most powerful warriors in the galaxy and how the traditions have come to be. It is mythical and beautiful.
The Nikopol Trilogy by Enki Bilal: Distant future and Ra has returned to earth because he needs to procreate so his lineage is preserved. There was a weird movie based on it call Immortal, half animated and half CGI character but before they could do that properly, so it's very visually weird but very well made.
There is also TONS of Marvel sci-fi, with stuff like Fantastic Four, Iron Man, Guardians of the Galaxy. Too much for me too list. But I hope this starts you off well. Oh, at some point you should read Understanding Comics by Scott McCloud, it is one of the only good analysis's of the comic medium and is a must read for fans of comics. Happy reading!