3 mins on and off is a good way to start WP. Fartleking is also fun. This is where you pick out a landmark like a lampost or postbaox and run fast to it then jog recover before the next challenge.
It depends what sort of person you are. I like my speedwork structured and measured now so I go up a track and run on distance (200s, 400s etc) rather than time (30 secs, 1 min etc).
All speedwork will make you faster to some extent so keep up the good work.