no seriously . youve got 3 numbers in the bottom line .
its all about thinking of the vertical as well as horizontal .
so bottom row .first one cant be the 6 . fifth one cant be the 6
so you know the no.6 on the bottom row is next to the 5 .which means the no.6 in the next row up must go next to the no.3.
so i tend to go for a certain number .
but im no expert and theres probably an easier way
good luck
I divided them up into 6 boxes of 6 squares in each then worked out which number went where without being the same as the one next to it. Well I think that's what I did!! :o)