The thing to do,to get looser,is regularly every day for ten minutes.Dont push it,just relax into it,and feel the stretch.Over a period of a couple of weeks,you will notice a marked improvement.
Stand straight,feet shoulder width,and gently bend at the waist,hanging your arms down,and seeing how close to the floor your finger tips are,just using your body wieght to lower.Take note of how low you are.do this for ten mins a day,gently,and you will begin to see your fingers getting closer to the floor.A little stiffness may happen,down the backs of your legs,the next couple of days,but probably not too much,as long as you dont push it,like i said,relax,breath out and lower gently,hold it a few seconds,or until you start to feel uncomfortable,then slowly raise,repeat as often as you feel like,but do it for a minimum of ten mins a day.But remember GENTLY.You can do a similar realaxed technique with most exercises shown you by others.
As a veriation on this,place one foot over and across the other,so your cross legged,and repeat,but this focuses on the hamstrings more so,so again,very gently,and slowly.