When I finished my rough draft, my story was around 84,000 words. I'm about 40% of the way through the first revision, and right now I'm sitting at 77,000 words. I'd guess that by the time I'm through the first revision, I could quite possibly have only 70,000 words. Is this a problem? I can make it longer, but should I do that for the sake of the word count?
Depends on the genre, mostly. I can't imagine it being a problem for literary fiction, where relatively short novels are quite common, but for something like fantasy, the expectations tend towards longer novels, often over 100,000 words. I don't think you should deliberately avoid adding anything, because after finishing your revision you may decide that certain additions could improve the work, but I wouldn't worry about adding for the sake of adding, at least not until you have a publisher or agent saying that you should add.
It's much easier to add stuff than subtract it. Believe me. I had the opposite problem and it cost me blood sweat and tears. If your novel happens to be YA, 70,000 would be good, incidentally. So, anyway, arron89 is right. It's not like an agent or publisher won't read it 'cause it's too short--they know it's easier to add, too!
heather's right in re YA, but for historical fiction targeting the adult market it may be a problem, since that genre will often be longer than others... however, if the story is good enough and the writing is good enough and you have an effective query that gets agents to read the ms, it shouldn't be an insurmountable problem...
Sounds reasonable. I don't want there to be any problems though, so I'm thinking I should try and get to 80,000 words. I don't think it'll be that difficult.