Your wedding cake will be a sizable chunk of your wedding budget, although there are some tricks to keeping the cost down. If you are having a lot of guests but cannot afford a multi-tiered cake to feed everyone, then opt for a single tier with decoration and keep some plain cutting cakes in the kitchen. After doing the cake cutting ceremony, your guests can then be served slices of cake from the cutting cakes - they will never know the difference and you will save money!
If you your wedding is in the fall and you plan to theme it accordingly, then your wedding cake can be a good place to start. As this will form one of the main focus's of your reception (alongside yourself of course) you can coordinate all the other elements such as decorations, table centers and wedding favors with it.
Here are a few ideas for a fall inspired cake:
An obvious element of fall is leaves! Take your colors from them as well, such as golds, reds, oranges, browns and yellows. Do some research on different leaf shapes and choose one you like or several different ones if you prefer. A good place to start would be with trees that are local to you or the perhaps grow near to you.
Your wedding cake could be covered with plain white fondant and then decorated with cut out leaves or feature a garland of fondant leaves draping down the tiers from top to bottom. If your budget won't stretch that far then ask for leaf shapes to be embossed onto the plain fondant and have a fondant topper made with different colored leaves.
You can then use the shape of those leaves as a motif throughout the rest of your wedding details such as your stationery and favors.
If you prefer something much simpler then look at having a chocolate cake with fondant bands in fall colors. Or have the cake embossed with chocolate leaves.
Decorate your cake with fall fruits such as blackberries which could be served up alongside each portion.