Do 5 sets of 1:00 each. You want to do the maximum number of pushups you can for each 1 min. set.
You can also increase try varying hand spacing (narrow and wide) or putting your feet up on the bench. Normal pushups will then seem easier.
Make sure you set up correctly for your test pushups: hands just outside shoulder width and even w/shoulders when you're in the up position. You want your weight evenly distributed on your chest, shoulders, and tris. Try breathing every other rep.