Make sure your oil is hot enough - drop in one chip and wait until it is bubbling nicely before you put the rest in the pan. The secret of crisp chips is to dry them with a tea towel before you put them in the oil, then check on the colour until they are as brown as you like them. Change your oil regularly, and keep the pan clean - and you should have crisp tasty chips every time.
I would recommend you stick to the tips offered by the guy who answered this before me, but also for perfect chips I tend to fry them twice: once at about 140�, taking them out of the fryer as soon as they start to have a bit of colour, then stick the fryer on max (about 190�), shake the chips about and once heated up pop them in until your preferred colour.