Slip Cover Patterns

I need help finding a slipcover pattern, or some advice on making my own slipcover without a pattern.  I want to recover a chair-and-a-half that's an awful, dark, mauve and hunter green color right now.  Ewwww.  I want to recover it in a simple ticking stripe, so I'm sure that's going to be extra tricky.  I don't want to just drape the whole thing in fabric, but would rather recover the seat cushion, the back pillow, and then the main frame of the chair.  Any suggestions?  I'm a beginner, though I tend to be a "just figure it out as I go along" kind of seamstress.  Thanks for the help!

A commercial pattern isn't likely to fit. I did it by cutting patterns of old sheets pinned to the couch. Sharpie marker on sheet, and remember to add seam allowances.  While you have the sheet pinned to the chair, draw your stripe direction or indicate top and bottom in case of napped or directional fabric! Some of the big pieces (flat cushions and the back of the couch, which was a plain rectangle), I just measured instead of making an actual pattern piece. You still need to make notes for stripes, etc. REMEMBER TO ADD SEAM ALLOWANCES!

Hope that helps... It's easier than it sounds.

That's sort of that I figured I'd have to do.  i think making a "muslin" will help me actually visualize how much fabric I'll need.  Thanks!