I have had to do this once or twice early in my “career”. I can tell you the difference to what I was used to was a bit bigger than house to hip hop though. I skip listened to a whole lot of samplers to get a feel for the genre. Then bought the ones that sounded best to me. Called a few people I knew were into that kind of music (not DJs) to get a few pointers about all time hits and such (remember, there was no Google, well no internet for that matter). Actually got to borrow a few records (and taped them … yes, on cassette tapes, for future use).
I think I spent a grand total of about 5-6 hours in preparation over 2-3 days. The gig went pretty much ok, where you go wrong is not having a lot of material. So hardly every other request you have to go “sorry, don’t have that one”. I knew I was going back to it a few times, so I noted down the requests and made sure I had them next time. Most of my first night wages went into buying the vinyl, after that it was all uphill.
But yeah, the most important thing is do you a) like the music at all, even if you never played it before and b) can you see yourself do more of these gigs? If the answer to either of them is no, don’t bother. It’s not worth the effort.
Greetinx.