Trouble with card from supplier

[shaz]

Hi

I am having serious trouble with card that I am getting from my supplier which does not have right angle edges.

Only when I start cutting down things like business cards do I realise how out the card really is.

I understand that some printers 'square down' their media when they receive it... but I just dont get how to do this.. I put the paper in the guillotine.. aligned the left edge.. trimmed a few mm off from the bottom.. repeated the same step for the other edges but the sheet just gets worse?

Please help!! Thanks