Hug her a lot. Hugs make women feel loved and secured. You'll never know exactly what your wife has gone through in her workplace during the day. A tender hug can lessen the stress she feels at the moment.
Help her whenever you can. While wives are expected to support and provide aid to their husbands, they're still humans with limitations - prone to get tired and sick from too much work. Help her with the chores or anything she does for the family without even asking if she needs help.
Have a regular couch time and listen to her stories. Kids are not the only ones who need someone to talk and share their stories with; adults need their personal stories and hurts to be heard too. Make it a habit to talk with your before you both go to sleep. Cuddle each other as you exchange thoughts.
Forgive her fast. It may seem like she could do everything for you and for the kids. But she's still human who makes mistakes. She might forget things you asked her to do or she might break one your valuable possessions. Forgive her quickly for whatever she does wrong and think of all the good things she did and continue to do everyday.
Hold her hand in public. Make your wife feel proud about herself and your marriage by holding her hand in public. If appropriate, don't be scared to cuddle or show other ways to show affection to your wife in public.