田字格 Chinese character practice notebook
various publishers
The square-with-a-cross grid that Chinese children learn to write in, and the reason it exists is proportion: the cross shows you where the centre of the character falls, which is the thing beginners get wrong and cannot see themselves getting wrong. Buy one with reasonably large squares — around 15 to 20 mm — because small squares force you to write fast and sloppy at exactly the stage where slow and deliberate is the whole point.
What it does not do: It is blank paper. It will not tell you the stroke order, correct you, or give you anything to write — you need a character list and a stroke-order reference open beside it, both of which are free on this site.
Free here first: Print the same grids, free