1 - Control your time. Take a good hard look at your daily schedule and then begin to tweak it so that it is more manageable. You may have to say "no" more often. It is amazing how cutting out just 1 activity a week can provide more down time for yourself.
2 - Don't Sweat the Small Stuff. I know this is easier said than done, but learning to let things go once in awhile is key. So what if the house goes 1-2 days without getting vacuumed or the laundry is put on hold for an extra day. It is important to alleviate some stress that we put on ourselves to get ALL of those little things done at once.
3 - Get Help. If you get to the point where you are feeling overwhelmed with your personal and family obligations please get help. There are many places that offer babysitting swaps, you can hire a teenager to help with small cleaning tasks or go to a friend for support. Delegation of tasks is another way to get help. Be sure to use all of your resources and delegate some tasks out to others.
4 - Clear out the Clutter. I know you have heard this one before but I can't stress it enough. Clearing out your clutter is a huge step in living a more simplified life. Make the time to go through your home and sell, donate, or throw out items that you no longer use. This is a large task, so don't try to do it all in one day. Try to set a goal of doing some every week.
5 - Simplify your Meals. Start preparing dishes which will provide several meals. Stews, casseroles, and many other recipes are just as easy to prepare in large portions as they are to prepare in small portions. Meal planning is a money, sanity and time saver - what else could a busy person ask for?
6 - Take Care of You. During the course of your day be sure to take out time to relax. Carve out at least 30 minutes a day to take a break, stretch or go for a short walk. Be sure that you are getting the proper amount of sleep so that you have the energy that you need to face each day.
Remember that your life is blessed with many different aspects. Keep them all in balance, and they will all be of much greater value to you.