Good, clear idea Mia.  Start by having a look at these articles for ideas:

http://www.aber.ac.uk/media/Documents/short/toyads.html

http://www.aber.ac.uk/media/Students/lmg9307.html

http://www.aber.ac.uk/media/Students/lmg9305.html

Also other articles here:

http://www.aber.ac.uk/media/sections/advert02.html

Sean