Straddle sits are extremely helpful. Try kicking one leg up on the wall or a door way. You can also stretch into your over splits but be careful not to pull anything when doing this. Do pike stretches to stretch out your hamstrings because flexiblity there is also important. Wall splits also help. You could get into a straddle sit and push yourself up against the wall. You could also put the back of one foot against the wall, place your hands on the ground, kick your other leg up on the wall, and push yourself against the wall. Also try just sitting in your splits, even if you don't have them yet.
Just sit in a spit position for 3 min at a time 2 times a day every day and you should have it in a week
Hope this helps :) and goodluck
Do wall splits! I always do that, remember to strech everyday! It helps!
Lunges and in your lunge straighten out your front leg and touch your toes. For middle do the frog