As for models, props make a great motivator. I have rubber swords, capes, crowns, spyglasses, and more that I collect from flea markets. Those who volunteer for a few drawings get the same credit as those who draw. After a few giggles, they get the point. It helps to tell the model to not look at other students.
The fashion portion is based on the packet I have made available for download. It includes some gesture drawing samples as well. In it we discuss the idea that there should be a central theme to the work to include the art principle of unity. The designs can be unified by a color, pattern, or idea. The only theme I do not allow is "Stuff I Like." When students complete their writing, I go around the room and ask them to share one theme and ask other students to write down anything they feel might work for themselves as well. Some common themes students often pick are specific colors, seasons, sport themes, and music.
We do a simple sketch for 3 looks before going onto final paper. They need to weed down to one theme they like best and pick inspirational swatches or sample for their final project. Work is organized by folding the paper, in half and half again to create four vertical sections. Final project must be to scale though they can choose a 10 heads model or 8. It becomes obvious quite quickly who has drawn some fashion ideas on their own and have an aptitude for it. I always say that by the end of Art 1, everyone will find something they do well. Some will surprise themselves with their skills!