Open Question: Starting a business with a friend?

I am in junior high and I'm going to start a business. I had color flyers printed at kinkos and everything. My plan is to offer services (such as yard work, cleaning, dog walking/dog care, babysitting). I am planning on charging fees varying from $5-$8 per hour, depending on the task and circumstances (babysitting would be more expensive than dog walking, for example). In the past, I've had businesses with friends, but it hasn't worked out well for a number of reasons. The first one, we were very young and it didn't work out, but the second time, I think it was because it was hard to manage business and friendship and not let our friendship be drowned out by the business. Also, one of the two others I did the last business with really didn't grasp concepts of business very well. With my new business, I was considering doing another business with friends, but I'm not sure if I should or not. Actually, I have two other friends who have been trying to do business but have been unable to keep it up (I am ambitious enough to take charge if nobody else will, which is both a strength and a weakness), and a third friend who saw a flyer on my fridge and wanted to do it with me. I told her I wasn't sure about doing it with friends yet. What are the pros and the cons of doing a business with friends, for a middle school girl? Please be thorough and tell me what you think. Thank you. Please DO NOT advertise ANYTHING to me. I'm not interested in any products or programs, and I won't call you or email you.