How can a I make my layer cakes not lean to once side?

I have recently became interested in baking layer cakes, but after I stack them and then ice it, later it starts to lean. How do I make sure that it doesnt lean so it will pleasing to the eye?How can a I make my layer cakes not lean to once side?
You need a cake leveler you can get it at Joann's or Michael's (craft store) if you have one or may be able to get one at your local big chain store (may be a bit more $$ than the craft store) You can also get a plastic disc that sits on top of first layer and a stand for teirs. Like I said Michael's or Joann's should have the supplies you need. Freeze the cake before you frost it, it won't crumb up as easily, you just brush the loose crumbs off first ( friend who did it professionally gave me that tip) You can also use small dowels to keep the cake in place (saw that on the food network ) or long tooth picks. Happy caking!!How can a I make my layer cakes not lean to once side?
When it's done baking, cut off the round part so it's flat and then use stiff icing between the layers, but not too much, JUST enough so that they stick. Line them up so the from the side they look straight and so that from the top you just see the topmost layer. I hope I helped you!
I cut the round parts of so they are level then brush the crumbs off with a pastry brush and sometimes when I'm making a cake with many layers(if not thin layers) I use shish kabob skewers to keep in place.
Was thinking of most of the answers already posted...is your oven level ? could be another reason...just a thought.
you have to make sure the layer are level before you stack. take a sharp knife and run it over the top to level it.





then apply a crumb layer of icing. that seals the cake. apply filling to the center stopping about a 1/4 inch from the edge then plop the top layer on. you can then ice the rest
After you cool the cakes, take a serrated knife and cut the top until even. Some cake dome a little. Make sure the cake is cool before frosting and that your not putting to much frosting in-between the layers.
Use icing to cover up imperfections...and the layers don't have to be directly on top of one another.
Put the bottom layer upside down, add frosting to top of it and then put top layer on right side up. That way it will be a flat surface between them.