Hi tintin. Congrats on your coming marriage! Ok, this is roughly what needs to be done:
1. attend Engaged Encounter or Marriage Preparation Course
more info at:
http://www.familylife.org.sg/about/whatwedo.html
2. prepare church booklet (after you've done so, let the priest who is marrying you look through the contents before sending to print)
3. you need to look for a choir, commentator, friends to do the readings and 2 witnesses - 1 or 2 weeks before the wedding, get permission from the parish secretary to have a rehearsal in church. You also need friends to do ushering and to man the reception table.
4. prepare and send out the church wedding invitation
5. engage caterer and florist - some churches require you to use their in-house florist, so check with the church first
Hope this helps - I got married 6 years ago + after having 2 kids, my memory is a bit hazy! Feel free to ask questions - they may jog my memory!
Good luck!