Sticky stuff remover works well, my mum got me some from kleeneaze book, works a treat! Even the magic sponges work well to I found.
We once did a massive B&Q store - every pain of glass had old tap on from posters, problem was the posters were massive so alot tape was used as the sun would make the posters full off. When we started the what I thought 5 hr job - found it wasn't normal tape used by industrial carpet tape!