The World Cup is the biggest betting event you will ever see. Not only are there 64 matches to bet on, but 30-50 markets on each match depending on which bookmaker you use, and then there are all the specials markets as bookies strive for a bit of variety to draw in new customers. It is these specials markets where punters should look hardest - since they are lower profile markets, bookmakers will spend less time in creating them and are more likely to have a different price to other firms.
When it comes to match markets, all bookmakers use odds monitoring services - there are not going to be huge variations between odds. Match markets are heavily based on intelligent statistical models which, in the long term, are very difficult to beat. But when bookmakers cast their nets far and wide in order to lure a few more customers, they will offer markets which can't be analysed scientifically - just by personal opinions, and this is where an advantage can sometimes be found.
Take a look at some of the special markets being offered: