Just keep in mind that new runners often encounter knee, ankle and joint problems so stretching effectively is vital, as is building up slowly. Some fun facts about stretching:
-- A number of recent studies have shown that stretching cold, that is to say prior to any exercise is useless. Warm up with at least 5 minutes of light cardio, stretch, do your work out, then stretch again after your work out is done.
-- When stretching avoid jerky or "ballistic" movements. A lot of the stretches you may have done in high school gym class may have been ineffective or even dangerous. The coolrunnings stretches (
http://www.coolrunning.com/engine/2/2_1/126.shtml) are OK but absurdly overambitious, if you did 12 stretches for 30 seconds 3 times each, you'd spend 30 minutes of your workout stretching which is about 3 times more than anyone I know, including marathon runners. I recommend finding a calf, hams, quad, and lower back stretch that you like and doing each at least twice cumulatively for 30 seconds.
-- There's a bit of debate on how long to hold stretches for, but most of the physiotherapists and trainers I've read who know their stuff say the ideal time is 30 seconds. Above 30 seconds and muscle fatigue sets in, and you stop benefiting from the stretch. Below 30 seconds can work, but you'll just end up doing the same stretch more times.