If you tough it out and take the time and devotion necessary to learn the trade, then you won't find a more rewarding job in the film industry. Editing is truly where a film comes together. The script can be entirely tossed out the window if the editor chooses, in order to mold the story. You could give two editors the same footage and the same script and you might very well end up with two different genres of films.
Needless to say getting started can be very intimidating and for many at-home or aspiring editors it's a daunting task. However, I've compiled 5 important tips to keep in mind that will help you:

1) Education
I think this one goes without saying. Believe me, I know there are plenty of people in the world that have created wonderful videos without having to go to any official classes. Just search YouTube or Vimeoh and you'll find these guys all over the place. However, figuring everything out on your own is the hard way to go about it, and could set you back several years. Before I went to college I did a lot of editing experimentation and was able to find ways to do some impressive stuff.
Then I went to college. I found shortcuts that not only allowed me to pull off the same edits and effects, but I learned how to do them better. And I'm talking about simple shortcuts that took all of 5 minutes to learn how to do. Before, I had spent hours (sometimes days) of digging through the Internet and fiddling with the programs before discovering my long, round-about way of doing the same things. It's time that I could have spent learning a more difficult technique, or actually editing my projects.
That's not to say that you shouldn't use the Internet and other resources to expand your knowledge, but starting with a good solid base is the key to being successful without having to waste a whole bunch of unnecessary time. Take some editing classes, even attend a few seminars on it, but make sure you get a grip on the basics of editing (both in concept and the basics of the program you're using). Once you have the fundamentals down it's far easier to experiment and try your own techniques.

2) Pick Your Platform
One of the first things you'll need to do, (normally it's something you'll discover during your education) is pick your editing pleasure. Final Cut, Avid, Adobe Premiere. These are the main choice you'll be faced with. Are there others? Sure, and if you want to go with those, by all means. However, those three are typically considered standards in the industry on some level.
Everyone has their own opinion on each program, but the truth of the matter is you can't go wrong with either of them. It's all a matter of what program fits your editing style the best. At first you really want to pick an editing platform and stick with it. Make sure that you have a really good grasp of the program and all of it's nuances before trying other programs. What this does you is give you a base of knowledge of how an editing platform works.
Once you have really gotten a program down (I hate to say 'mastered' because it's ever changing) then I would suggest branching out and experimenting with other programs. Sometimes you might find yourself working with a client in their studio or place of business who only uses Avid. Well if you've only ever used Final Cut of Premiere for years, then you might have some issues adjusting to the layout, which could cost you precious time.
Let's face it, all editing programs are fundamentally the same. The main differences come in the interfaces and layouts, but they all serve the same function. So making the switch isn't terribly hard, but it's always good to be a step ahead. Don't try and learn them all at once though. It'll only confuse you, and make the learning process take much longer. Start with a base first and then build outwards.

3) Ask For Help
Just because a lot of the job requires solitude doesn't mean you should exclude yourself from others. In fact this means you should be more willing to go out and ask questions from others. The editing community is filled with people who want to reach out and help others. We know just how hard it can be, so are willing to pass the knowledge on to anyone who wants to learn and listen. If you can find such a community online, or even find a few people in person with editing experience, it might not be such a bad idea to put them on your contacts list.
Take the time to find out what their specialties are, so that if you end up working on a project you're not sure how to do something, you'll have a list of people you can call on who might be able to provide that help. Never be afraid to ask for help on an issue. We've all been there. Only a couple days until deadline and suddenly the client decides he wants to throw a curve-ball at you, with an editing technique you've heard of, but have no idea how to implement. This isn't the time to fiddle around yourself trying to find a solution. That could cost you a lot of the time you need to finish the rest of the project, and if you miss the deadline, it'll cost you money and a client.
Hopefully you've been able to find a good group of editors to associate with and exchange contact information, so you can fall back on these people in those times of dire need. If you listened to my first tip of advice, then I suggest maintaining some sort of relationship with your professors. To this day I still contact my first semester college teacher when I run into a particular problem. It's a stable source of advice that can always be there in a clutch situation...use them!

4) Use the Internet/Continue Your Education
We've talked about getting your education first, and not solely relying on the Internet to learn everything...but that doesn't mean it can't be a good tool. Once you have the knowledge, the Internet can be a wonderful way to expand your education. Editing is a constantly changing field. As technology continues to get better and better, so do the choices we have as editors.
It's important to stay current with the trends in editing, because the newest thing might be exactly what your next client wants. The Internet is filled with websites dedicated to the field of editing, and providing a constant stream of tutorials (video and written) that could help you learn new tricks and stay on top of your game. More than just that, even the best of us forget things at times. Something so simple might totally slip your mind one day, and at that point it's a good idea to have some websites in your bookmarks for such things. If you're more of an older soul like me, then it's also a good idea to stack your bookcase with the latest tips and technique books.
In order to truly keep up with the times, you can't finish going to school and say "OK, I'm all done." Unfortunately we're never done learning in the filmmaking business so attending new seminars are day classes at times are necessary. You can learn quite a bit (or refresh your memory) and they're a good way to meet new people and continue developing that contact list you have going.

5) Learn When to Take Breaks
A lot of beginning editors try get everything done immediately. They end up working themselves through the night early on, and just wear themselves out. While it's important to make your deadline, it's very important to make sure the product you're putting out there is quality. None of us do our best work when we're exhausted. Let's face it, decisions you make at the start of the day aren't the same as the ones you make 12-16 hours later. Some of the things you do in the wee hours of the night might seem brilliant to your tired mind, but in the morning you're left trying to fix all of the mistakes you'd made.
It's important to take breaks and let not just your body, but your mind rest. If your mind doesn't rest you're more likely to make mistakes and miss things you wouldn't normally. Plus, any artist will tell you sometimes you just have to step back from the project in order to gain a better perspective on it.
If you've been working on the same scene for hours on end and it's just not working no matter what you do...this is the time for a break. Go outside, play a game (if that's what you do) or even go out and watch a movie. Then come back to the project feeling refreshed and tackle it with a clean slate. DON'T just go onto another part of the project. I know it's tempting, but unless that deadline is the next day, you will only carry those same frustrations over to another part of the project.

There you have it. Are these the only tips you should follow? By all means no. There are so many other things that I could mention, but that's where your education needs to step in. Whether you're just getting started or a veteran, these 5 simple tips should help you traverse the ever-changing world of post-production.
-Jordan