How to set out a floor
Basically you will need to find the centre of the room. If it is an odd shape, work with the biggest oblong part as it will be most visual. Start by measuring the length of the room from both sides, halve each measurement (generally they will vary slightly) and mark it on the floor at both ends. Join the two marks up using a chalk line and then do the same for the width of room. To check that the lines are square to each other, measure from the centrepoint that they cross as follows: 300mm along one line and make a mark, 400mm along the other and make a mark, then measure between the two marks. It should measure 500mm if it does not then adjust your centre lines until it does.
Lay a tile squarely into one quarter of where the two lines cross and work out what size cuts you have to the four walls. If you end up with a small cut put the centre of the tile on the centre point of the floor this should allow you a bigger cut. You will need to try various options to achieve the best result. Setting out the floor is very important so take your time and always check your measurements.