The way things are going in publishing nowadays, you're going to need to stick to wordcounts when it comes to selling your work, be it a short story, novella or novel. For each of these, publishers will have suggested wordcounts.
Speaking from personal experience, an ideal length for a novel nowadays is anywhere between 60 000 to 90 000 words. The reason for this is that print-on-demand (PoD) is turning out to be a viable option for small publishers that don't want to take unnecessary risks with regard to their printing options, and any book that has more than 90 000 words is going to cost quite a few pennies more compared to its brethren brought out by the larger publishers. This won't help you if you're relatively unknown and are suddenly competing with big names. Your first novels need to be affordable—an incentive for people to part with their clams if you pique their interest.
So, if you're a fairly new author, who's most likely going to get their first chance with a small press, you need to aim for the wordcount on a publisher's submission guidelines if you're going to have any hope in hell of selling your first novel. Sure, we occasionally do hear of the Jacqueline Careys out there who sell a 600-page whopper for their first deal, so yes... those kinds of stories do happen, but rather take some of the pain out of your life and aim for something that won't have editors and agents all saying no before you've been given a half-decent chance.
Before you start cutting scenes and mangling your work in a desperate attempt to cut a few thousand words, I have learnt a trick that will help you. Not so long ago, I was faced with the problem of reducing a 104 000-word novel to under 100 000 words. I was not happy with cutting scenes, as there weren't any I could remove without losing some of the work's impact.
Without worrying about the scene progressions, I first read through the entire novel (again) and started looking for words that were repeated. The most common culprit was "that". It's one of those invisible words that escape notice and, more often than not, authors (myself included) tend to overuse this little word. You'll find some of your own. Trust me.
Another culprit is sentences that start with "There was". Go look at that sentence carefully. Cut "there was" and rearrange your sentence so that it makes grammatical sense. Ten to one, this will be possible and you'll find you'll have lost a few more words.
Look out for repetition. Many authors I've edited will find two ways of saying the same thing. Granted, this is not always extremely obvious unless the author is absolutely abysmal (and trust me, some people truly are...), so read over a suspicious sentence then ask yourself if you're repeating yourself.
Pet phrases: everyone has them. One I've recently encountered was "All too soon" at the start of a sentence. As an author, it's easy to overlook these but all it takes is a fresh pair of eyes and you'll be sure to find them.
Empty words: "really", "virtually", "very", "literally"... You should highlight these words in bright screaming red in your brain. They have their uses, perhaps in dialogue, but because often we write the way we talk, they do creep into narrative and waste space. In many cases you can hit the delete button, thereby strengthening your sentence.
Also, watch out how many adjectives and adverbs you're putting away. In many cases you can lose a few without harming your story. Keep a special watch out for words ending with "-ly". You can lose a few here and there. Trust me.
Then the difficult bit... You've gone through your MS for the nth time and now you're only a thousand words over the required wordcount. Wow, congratulations for getting this far without cutting scenes. Now you're going to have to lose a few paragraphs here.
How to choose? Don't be precious over your words. Your editor (bless her heart) will in all likelihood be making you do horrible, terrible things to your MS. Now's not the time to be squeamish. Look at your scenes and wherever you find you've got a lull in the story, look for non-essential information you can lose. Also, keep a special look-out for exposition.
This is any information that is given for information's sake, or if you're trying to cram in back-story. If it's not immediately necessary to the narrative, lose it. Many newbie authors try to turn their first chapter into a Condensed History of Everything, which usually succeeds in sending readers to sleep. If this stuff is important, you can weave it in later, in small, digestible pieces.
As an example, in my novel Khepera Rising, I lost more than a thousand-odd from the first chapter. My beta reader, who is a talented author, was merciless, selecting chunks of text whenever she felt the story's pace flagged or my protagonist was being verbose. I took her advice and cut. I kept earlier versions of the MS, just in case, but you know what, I'm still not missing those bits and the story is much, much stronger for the excisions.
Lastly, remember that a novel will be revised quite a few times before it is released. If you are diligent before you begin the editing process with your publisher, you will make things much easier for yourself in the long run. When your editor gets back to you with any of your personal writing quirks (which you do have, don't bother denying it), pay attention then make sure you apply those changes to your future works. If need be, write them up with magic marker and stick them on your noteboard above your desk.