For FONDANT covered cakes, I like to chill the crumb coated cakes before I put the fondant on them. I do this only because I have found that after smoothing the fondant with my hands, the icing will tend to ooze out from the bottom of the fondant or move around under the fondant. So this helps in preventing that.
For multi tiered cakes, I like to use FOAM CORE BOARDS as a base. I get them at Michael's in the framing dept, they are usually on a shelf with other boards of different thicknesses. I prefer to use Elmer's Foam Board 20 x 30 x 1/2 inch. I like them because I can cut them to any size and shape with an Exacto knife, and they will support the weight of the multi-tiered cakes. Next I use some of Wilton's decorative paper to cover the board and make it look pretty. I often get ribbon to match the color theme of the cake and them either glue it or use straight pins to cover the edge of the cake board. I just think that it "finishes" the board and adds to the cuteness.
Start with your bottom tier, and cover it with your fondant, add any fondant decorations that may end up under your next tier. I know this sound silly, BUT if you'd be suprised how many times I didn't think of that when I made my first couple of cakes!
Once you have your bottom tier covered in fondant and ready for placement. Take a little buttercream and smear it on the cake board where you want to place your cake. Place your bottom tier and then get some wooden dowels (I use Wilton's) and measure them against the tier. Cut them so that they are either level to the height of the tier or a little (I'm talking a smidge) over. I then get a pencil sharpener (I have one solely for my cakes) and I sharpen one end. I then place 4 wooden dowels into the cake in a square into the tier. These will then support the weight of the next tier. Your dowels should end up level to the top of the cake, or just a bit above. If they stick out too much you will end up with a gap between the tiers. This is ok, if you will be placing gumpaste flowers or fresh flowers inbetween the tiers.
You now have your bottom tier ready and done.
Now you can start working on your second tier. Now you just repeat what you did for the bottom tier on all the following tiers you have to make for your cake.
The only thing you won't need to do is putting buttercream inbetween the tiers, your cakes will stay put because you will be placing one long dowel down the center of your cake once all the tiers are in place.
I unfortunately did not take a picture of the center dowel, but all you do is take one regular dowel, I have found that these will generally be long enough to stake the cake, or you can get a longer one from the modelling section of Michaels. Then you just take it, hold it against the height of the cake, mark it off like if you did when cutting them for the lower tiers. You will want this one to be slightly shorter than the actual height of the cake, because once you drive it in, you can not pull it out to cut down. (I've done this before and it sucks!!!) Now that you have your center dowel cut to size, use your pencil sharpener to sharpen one end, like you did with the other dowels, and drive the pointed end into the center of the cake. By sharpening the end you will be able to drive the tip through the cake boards and anchor it into the foam core board!
This center dowel will keep the tiers from sliding around or shifting.
THIS IS CRITICAL IN KEEPING YOUR CAKE STABLE FOR TRANSPORTATION!!!!
I forgot to place the center dowel in a two tier cake once and the top tier SLID OFF THE CAKE as I transported the cake for delivery.
So there you have it... how to make a multi-tiered cake step by step.