Single mum of two ... 2 girls 9,10 and moods.

Hey I.M's
I'm looking for some advice on how to deal with my 10 year olds mood swings, and attitude problem.
We've been a single parent family for 5 years. Without any issues but just recently I'm finding it very difficult to firstly either punish or support the moods swings and attitudes.
Now my 9 year has started as well. It causing me so much stress. Anyone know how to deal with a child approaching puberty?