Find a type of juniper of reasonable size that grows well in your location, choose a plant with a reasonably straight stem. Cut away side branches at the base and the middle leaving the pom-pom parts at the top and middle. You may want a support of bamboo or wood stake to hold the stem straight. It takes time, but one season's growth gives you a fairly nice shrub depending on teh size you start with, allow for repeated clipping of growth to fill out.
Reminds me of the sculpting joke: student-"how did you make the sculpture of the horse?" artist-"I cut away everything that didn't look like a horse"
a good book is Topiaries and Espaliers by Linda Yang, which gives step by step instructions.