I worked from home part time (3 days at home, 2 in the office...full days) for a number of years. It was a great set up and ended up working out well for both me and my employer. But we set a number of rules and guidelines up front to make it work.
Number one rule...you need to have someone to watch your child during your working hours. Your company is paying for you to work during that time, not take care of your child. It's easier to get your job done when you have someone to watch your child. The benefit of working from home will allow you to spend your break times and lunch with your child, something you can't do while you're working in an office environment.
Number two...have a separate work space preferably one with a door. When I was in my office, I was in the office. Period. I left only to take breaks.
Number three...I found it helpful to act as if I were going to work at an office...get up, take a shower, dress professionally. Because I took my DD to child care I made it a habit to go to breakfast with her, drop her off and then come back so it gave me the illusion of leaving one place and then arriving at work. If you have home care you might consider taking a brief walk or drive to get coffee or a paper to make the transition seem a bit more realistic.
Number four...separate phone line. It was hard to feel like I was at work with everyone calling me wanting to chat. You are working from home, not just hanging out. I got a separate line for my office and used that as my work phone. I could answer it as I would at my office and even forward my office phone to it on the days I was I at home so no one had to remember another number. Worked great.
Number five...make a schedule and stick to it. There are two ways to get in trouble working from home. The first is because you work from home people think you are always available, no matter the time of day. They may think nothing of asking you to do an assignment for the next day at 4:59 p.m. because, well, you work from home so your office is right there. The reverse is also true...you may be tempted to do other things during the day because your office is there and who really cares if it gets done at 10 in the morning or 10 at night as long as it's ready by the deadline. It's better to set all expectations up front and stick to them.
Number six...make sure friends and family understand that just because you are home during the day, you are not available for the pop-in visit. You are at work. They wouldn't just pop up to chat if you were in an office building and they can't do that now either.
Working from home can be a really great experience but you need to establish rules for yourself and others before you start to help you suceed.