sometimes it's tricky to get bottoms to stay in place, but you just have to work quickly and use very sticky goo.
to be more specific, usually for my bottoms I cut out a piece of cardboard after outlining exact footprint of piece. then i turn the whole thing over and quickly fold sticky paper strips from bottom over edge of piece. this usually works quite well. if you cant keep the cardboard from slipping, hold it in place with a few pieces of masking tape and mache everywhere else, leaving these spots for last. good luck.

best thing for shoes is to make a pattern as you would for a dress. trace it on thin flexible cardboard (cereal boxes are good) then off you go.

Found another way to do it, too. Where the base was glued in the centre, I supported it with small balls of goo as wedges between the centre and the balloon. It gave me enough extra @base@ to work round.

Jacqueline