I use pearl drops whitening daily toothpaste. I have been using it for about 2 weeks and have started to see a difference.
Read up before you use this bleaching internet stuff, some work but some just contain irritants to make your gums and lips pinker so your teeth appear whiter yet they make no difference to your actual teeth.
I tried teeth bleaching once, went to my dentist and spent about £300, made less difference than the toothpaste and it made my teeth sensitive for about 4 days.
I've been using a kit from superdrug called Brilliant, It's in a purple, green and white box.
You put the whitening gel in the gum sheild, Put the accelerator on each tooth your wanting to whiten, and without touching your teeth after place the gum shield in for 5 - 10 mins then brush with tooth paste provide. Works wonders
We were talking about whitening teeth at the tv studio the other day. One girl said it - in the long term - makes one's teeth over-sensitive. I wouldn't touch anything that bleaches your teeth if I were you - you might regret it when you are older and can't eat ice cream!