Preparing humorous speech toastmaster

Once bitten twice shy,  goes the adage
But I'm someone who refuses to learn from mistakes (own or others)
So I've decided to participate (again) in toastmaster speech contest (humorous) even though my last attempt was a complete disaster.
One of my invented excuse for last time was lack of time for preparation. This time I have more than a month to prepare (you can read about the last failure below)
The tentative topic finalized is (not) buying own house. Few reasons for selection of this topic as below
1) maximum people can relate to it
2) pain area for everyone still everyone has a funny anecdote to tell