Keep a workshop and/or an inspiration journal. I will use mine (an extra large Moleskine journal) for collecting interesting scraps from magazines (ads, fashion photography, etc.) which may inspire new pieces. Another use – and a very important one, at that – is sketching up these new designs and recording the exact measurements of finished pieces, as well as comments and suggestions. I do make cardboard patterns, but these tend to get lost or damaged over time, and it's proven VERY handy to have everything neatly in one place for future reference. Oh, and add a date to your sketches. It'll be fun to browse through your old journals and see what you were up to years ago. Maybe that piece you never actually got around to making a few years back will at once make perfect sense then.