Basically, a haiku should be composed of three phrases of specific syllable numbers which are as follows: 
5 / 7 / 5

It is way easier to achieve in Japanese than English because Japanese language alphabet is syllabic itself (one character stands for one syllable rather than one sound). Haiku should also be indirect like the whole japanese poetry. It is rather impressionistic than blunt. 

Here's an example I've found;

Whitecaps on the bay:
A broken signboard banging
In the April wind.