The amount of money anyone spends on their wedding very rarely adds up to what they planned out when they were creating a budget, it's almost always higher than what was anticipated. Overspending has more to do with the way you plan a wedding than the stuff you buy or rent for it. If you want a gorgeous wedding and under a budget you have to fix the way you're planning for it. There will be some areas where you're going to have to keep a somewhat generous budget like the reception but the right kind of planning will save you money in other areas.
You may spend days and days picking out the invitations, place cards and programs. If you have them specially printed out or designed, it'll cost extra. By investing half the time and money you would on buying wedding stationery, you can make it at home. It saves a lot of money and you won't have to worry about color schemes when you're the one who's putting it all together.
A great way to accommodate decorations in a smaller budget is to make your food part of the decorations. Find unique foods to serve like fruit bouquets or fresh fruit arrangements that are really decorative and look great as centerpieces. Using food to decorate your table instead of flowers will save you a ton on your wedding arrangements.