Many Elise owners want individuality. And then they give up and decide to fit stripes instead.
1. Deciding on colour / style Our most excellent SELOCer from France 'lolocb' has put together this nice summary of just about every stripe combination we've ever seen
There was also a groovy web page where you can choose the colour of elise, and then the colour of stripes. Sadly it isn't up any more (the link was  http://www.uyesugionline.com/Elise/eliseviewer.aspx)
2. Fitting If you fancy fitting yourself, beware - the rear of the car can be really difficult. However with patience and time, good results can be had. Alternatively you can pay an expert to do the job too. There are many recommendations on the forums.