Dude...
Your biggest responsibility in getting engaged and married is to do the engagement right. Every girl has dreamed for years of being a princess and getting engaged. While the wedding is the big day, you have got to make the giving of the ring into a story that is fun to tell. When your fiance' lets all her friends and family know the news, she will be twice as proud if you put the right effort into making the event unique.
Suggestions
1) Design the night around things that have meaning. First date, favorite romantic restaurant, things you love together.
2) Get pictures during the evening. She will want to remember it forever and will want to share the picture while telling the story.
3) Work hard to make it a surprise.
4) Plan ahead. It may take you a month of hard work to get all the details set. Stick with it. This is your main job.
5) Splurge on at least one big thing. Limo, event, trip, something. Besides the ring, you need to do something that she can talk about that says "Classy".