Tip 33 : Avoid humour
As mentioned earlier, there are no hard and fast rules for writing personal statements. With that said, humour is very rarely going to be a good option.
In the first instance, very few people are genuinely funny, so unless you're one of those fortunate few I'd highly recommend that you avoid attempts at humour altogether.
Beyond this, though, it's even harder to be funny in writing than it is in person, because you don't have the benefit of non-verbal factors such as gestures and vocal intonation. Moreover, in writing there's so much more scope for misunderstanding. Whilst there may be a very small number of instances where humour could be appropriate, I can't think of any cases where not including humour would be held against you.
Unless you're applying for a position as a cartoon writer. In which case, go to town.
Tip 34 : ...but be interesting
Okay, so you can't be clever or funny... But you do still have to be interesting.
Now don't get me wrong here, you're not trying to win an award. When it comes to personal statements, being interesting often comes down to the avoidance of being boring. If your statement is boring, or extremely long, you risk losing your audience before they're finished reading it. An unfinished personal statement will rarely be a successful one.
The best way to make your statement interesting is to stick to the points you're trying to make, order them logically, and be as brief as you can possibly be whilst making all the points you want to make.
That's all much easier said than done, but if you do manage all of the above you'll be well on your way to a very solid statement indeed.