Well im printing that post Gavin  and ill be heading to bunnings to buy them colors as im using white to lighten and black to darken. No wonder im having such a hard time lol

AAAAAAH!!! Yep - youll never match with that combination - also try to look "into"the colours... if you have what appears to be a blue but when you put a blue against it then appears slightly purpley then it has just a touch of red to it, if it looks greenish then it has yellow in it etc.
Always mix with tiny amounts also - if its a light colour then start with the white base and add to that - if you try to lighten then you will use far more paint than is necessary - its harder to lighten than to add tint