What's a good iPhone passoword?

Hi, I need a really good password that know one will guess. I have a sister that always gets my password. I don't know how?! Someone help!

Hi! I don't have a password in mind, but I do have really useful tips on making a password that will be virtually impossible for anyone to guess!
1) take a word such as golf, now this may seem a really simple password but if you change the o to the number 0 it's makes the password considerably harder, so instead of golf it will read g0lf! You can also add numbers at the end or even a few numbers, with a letter eg g0lf19o2, you can have written passwords on iPhones so this is probably the best option if you don't want your sister to get your password! Hope I helped!

Put a series of numbers on a table. Group 3 then 3 then 3. Or group 4 the 4 easy to learn and remember, but do not tell your sister, do not use your birthday or anyone else's, NO 123 456 789. Maybe 19532011, this means nothing to you but everything to me.