It's great that you're starting to think about planning your wedding early. The earlier you start, the less stress you'll have.
What I always suggest is setting down with your hubby to be and see what you BOTH want regarding your big day. Once that is established, its time to get your "maid of honor" and your bridesmaids lined up... and let the fun begin!! This is the time for you gals to really enjoy. Start looking for and trying on dresses. Work out color schemes. Please be mindful of your guy though. Many women tend to push them out of the picture and he shown no interest (or even requested to be excluded altogether) do try to keep him in the mix. Start researching venues, talk to rental companies. I can't stress this next tip enough.... MAKE AN "IDEA BOARD"... this is important because unless you have a crystal clear picture in mind, your bound to change things a time or two, and this could really save you money. Go to your local craft store, get a piece poster board... and design your wedding/reception on paper first. Cut pictures out of magazines, collect scrape of materials that you plan to use... put it all on your board. Make notes as well. Planning and organization are key to making things run smoothly further down the line. Utilize the internet... search places like theknot.com or brides.com; they have a ton of information, message boards and forums.
Getting a binder and a checklist would be a great first step, as well. You don't have to buy one of those big wedding planning books (they are useless and too expensive, in my opinion). You could just get a regular three-ring binder and put a checklist and some loose-leaf paper in it. As for the checklist, there are a lot of free checklists available online. If that one doesn't work for you, you can just Google "wedding checklist" and find one that suits you.
The most important things to do first are: book the church and the reception hall. Unfortunately, that means choosing a date (which is hard to do, I know). Once those two things are done, the rest will come pretty easily. Churches and halls are often booked two years in advance, so it's important that you lock in your date asap. Also, since you are getting married in the Catholic Church, you will need to set up your first appointment with your priest so you can schedule your classes and meetings, etc.
It's also important to set a budget for the big day and beyond. Has anyone, such as your parents offered to pay for part of the wedding? If not, if you'd like some etiquette help regarding asking them. So sit down with them or your to-be in-laws and see what they are willing to help the two of you with.
The next thing you might want to do is request a guest list with addresses from your parents and your fiance parents. I know it seems a bit early to ask this, but you'd be surprised how many people drag their feet on this; thus, makes the bride goes CRAZY! Next, you might want to figure out who will be in your bridal party and ask them to be in your wedding. If you have someone who is a bit short on cash, this will give her enough time to save her money.
Other than that, you can just follow your checklist and try to accomplish each point as soon as you can. Like I said, the earlier you start getting things done, the less stress you'll have.
Some things to keep in mind: Although you will probably need to bend on a few things, don't forget that this is YOUR wedding! Try not to let the many opinions of others get you down. YOU are the boss!
Have your fiance help! One good task to put him on would be the honeymoon plans. This will keep him busy and make him feel like he's doing something useful regarding the wedding planning.
Get your girls to help! The whole purpose of a bridesmaid is to support the bride. Ask one of them to look into halls, the other to shop for guest gifts, the other to find a photographer, etc. They will probably like feeling needed and their efforts will take some of the load off of you. But, if you put them to work, don't forget to get them a very nice "thank you" gift.
Relax and have fun. If I hadn't kept laughing while planning my wedding, I would've probably landed in the Looney bin. Also, when it comes to the big day, a relaxed bride equals a fun wedding. I don't care what the budget is...if the bride and groom are having a good time, the guests will follow.