You might not think there would be much to an article entitled "How to clash patterns". After all, you take two different patterns, wear them at the same time, and what do you know, you're clashing patterns! Well, if it were only that simple. True, it is very easy to wear patterns of a vastly dissimilar nature, or indeed patterns of a similar style but different palette, but not so easy to make them seem part of a cohesively abstract look. Yes, looking 'ironic' is simple, but it's also shit if you pardon my French. Far harder to take two or more strong patterns and be able to play them off against each other in a way that makes people think "that looks so good on him but I would never be able to pull that off." The fact is anyone can - it's just the matter of following some simple rules to clash patterns effectively...
Work with your boldest pattern. If you've got a favourite bold check coat, then don't try to outshine it with a red check shirt or tartan trousers. Give the coat its 15 minutes of fame. Instead complement it with a muted check, or pinstripe or chalkstripe suit, or some herringbone trousers in a contrasting colour. Understand what the statement pattern is that you're wearing and work around that.