Before you even offer to make a wedding cake for someone, make sure your heart is really, truly in it. No matter what, there will probably be moments along the way when you think, "Man, I really wish I hadn't signed up for this" or "Wow, buying a cake sure seems easy right about now." But if you're hesitant from the start, forget about it. Whether you want to do this as a unique gift for the bride and groom — and by the way, don't count on it being a cheap gift — or you love baking and see it as a fun challenge, know your reasons for committing to making a wedding cake before the sugar and flour start flying.
Depending on what kind of filling you're using, it can usually be made well in advance. But some frostings need to be made closer to when the cake will be served. Between the recipe and your practice cakes, you should have a sense of how early the filling and frosting can be made and how long they'll hold up. Once again, overestimate how much you need. Plan to bring an extra pastry bag of frosting to the wedding site to patch up any little cracks that happen while transporting the cake.
To get the positioning of the other flowers right, carefully place your top tier on top of your base tier. Unless it's been incredibly humid, the overnight drying time should have made the tiers safe to handle without messing up thier smooth surfaces too much. Any small marks can be rubbed out, or covered with flowers or a little imaginative piping.
Once cooked, leave the cake to cool in the tin. When cool, remove from the tin and place on some baking parchment. Drizzle a couple of tablespoons of brandy (or your other chosen liquor) over the cake and wrap it up tightly in parchment and clingfilm or foil. Every few days unwrap the cake to feed it with another spoonful of liquor, then wrap it back up and return to a safe, temperate storage space.