Stretch daily and stretch often. Lunges are a great starting stretch as well. Splits take time and you should never force your body too much. It's best to stretch often pushing little by little so you do pull a muscle or harm any joints.
Little by little, everything is on progress every day. even I have not mastered splits,and I don't have to, but to be able to practice new habit, stretching everyday, is making me more confident of myself, that I actually can do it, If I want to. Okay that's actually contemplation for fabulous in general
By Pushing pressure Onto your legs each day, They will be able to Stretch further Each time you try. One day, You will be able to do the spilts. It just takes time.