Well standard retail practice is to create 'hot spots' areas in the shop that a customer entering or moving round the store can't fail to see. At these points display the goods you want to promote. Also putting items for sale by the till really doeas increase sales. Do a back to school display in the window to draw peoples attention to the fact you actually sell these items - often in bookstores they are hidden away at the back and people often don't even know you sell them. Also - most infant and junior school age children have a bookbag at school, (ring local schools and find out how many classes they have and how many children ineach class, do a sales flyer and bundle them in to say 5 lots of 30 and ask the school to put them in the bags) offer a 10% promotional discount or a free gift - I use this as a way of promoting events so it should work for selling too.
Good luck