I have found that keeping one container beside the sewing machine with packaged ufos is great. I am more likely to reach for them than something new. The container holds more than one project, so when I get bored, I switch. It also creates a limit - if it is full, I need to finish/purge something to create space for a new project. When switching projects, make a quick note of where I left off in a pattern and put all the pieces/pattern in a plastic sack and into the bin for later.