How should I ask professor for letter of recommendation? I'm a freshman undergrad student, and I'm applying for some programs that require letters of recommendation. I already have one professor who seems happy to write one for me, but I have another who I don't know how to ask. In the past when I've contacted the professor, he has neglected to reply. He's quite busy and disorganized. Most people I've talked with have also had trouble contacting him. In addition, I am worried about asking because I have only had one class with him and I'm not sure he likes me or can actually write much about me.

I have a class with him starting about 3 weeks before the deadline. Should I ask now over email so he has time to look at it? Should I include information about the programs I'm planning on applying to in the initial email, or would that seem presumptuous? Thanks for any help!
If he's really your only option, e-mail him and ask if he'd be willing. Keep it short and to the point, just tell him you're applying for a program and ask if he'd be willing to write you a letter. Be sure to mention you'll supply him with a CV and any necessary info to write a proper letter if he agrees. 

Hopefully, he'll respond quickly and you can send the necessary info. But as @Roboticist mentioned, you'd really be better off finding someone else if at all possible, especially since he's ignored you in the past.