Ask people to be a bit more considerate about their bloody rucksacks! You could have hidden a child in some of the oversized sacks gleefully swaying on the shoulders of several attendees that quite literally smacked every single person they walked past. As a veteran con-goer I realise people may bring many treasures to get signed (and probably are carrying several litres of water, camera, folder for photos/autos etc) but my 8 year old was clinging to me after repeatedly getting hit in the head by gigantic bags.
In busy areas please take them off and hold them, wear them on your front, or, at least, on both shoulders to stop them swinging about! It's a simple courtesy that could make the busiest areas a bit more bearable.