"I do not like meat."
I'm still a newbie, but from what I've read, は is usually used when a sentence is negative. が tends to add some importance or emphasis to whatever word it follows, so the meat would be the most important part of the sentence if you used が. With は, the emphasis is shifted to the "not liking" which makes more sense.
"Do you like meat?" "にくが好きですか" "I don't like meat." "にくは好きじゃないです"
The "not liking" is the important new information in the sentence, so the meat just gets a は, marking it as already-known information. This shift in emphasis happens a lot when you turn something negative.
If there's a clear and obvious difference between ...はすき and ...が好き I've yet to detect it, but "が" seems to be slightly more common when referring to something specific that may have previously been introduced as a subject, or is less important that whoever it is doing the liking, or the fact of it being liked.