Organizing Time

I have a little dilemma that maybe my fellow crafters out there can help me with. I would like to know how you organize your crafting time--especially if you sell things. Do you devote so many hours per day/week/month to your craft or do you just craft when you find the time in your busy schedule? Do you write a schedule for the day/week/month? Do you make a list of goals that you want to accomplish for any given day?

The reason I ask these questions is because I read an article a fellow Twitterer posted that said if you treat your hobby like a hobby instead of like a business, it will never become a business. It said to set reasonable goals and to put yourself on a schedule where you can devote specific time/hours to your craft. I'd like to try this so I can see if it really makes a difference in my sales, but I'm wondering how best to do this. Should I set myself up to work a certain number of hours every week or play it day by day? Should I devote so much time to making certain items every week, or should I just make whatever I feel like at the time?

So, my question to you is: how do you schedule your crafting time and decide what to work on (if you make more than one type of item)? Do you have a set schedule? Let me know!