Fitting new timber windows

[Zebra579]

I'v'e fitted U-PVC windows before but am having new timber windows made for my house and would like to fit them myself. Is there anything I should know which makes fitting timber windows more complicated than fitting UPVC ones? Is there any more to it than marking where the fixings will be, drilling into the frame, fix with plugs and screws, bit of frame sealant round the edge..... ?
Many thanks

 

[foxhole]

You need to pack the sides before fixing to prevent distorting the frame.Also need to ensure it's true and level and the correct amount of frame is protruding.