If you colour your hair with dark auburn, (red/brown), streaks, it would still suit you as you have a strong red pigment in your skin, as shown in your face in the light blonde curl pic on the floor.
However, your skin is peaches and cream, slightly olive, so ash is generally the best.
http://www.style-hair-magazine.com/image-files/largeredhaircolor3.jpg
The best cut I would do is a wee bit shorter, with streaked or notched hair curling under your chin.
http://www.style-hair-magazine.com/blonde-hair-style.html
How to find the right colour?
http://www.wikihow.com/Choose-the-Right-Hair-Colour
Colour is a delicate subject. It is also not a full gone conclusion. Plus the fact that colouring can cause damage to hair if repeated too often, like every 3 to 4 weeks.
Your clothing also determine your correct hair colour and look. Paris Hilton looks best in yellow or a dark blue. You need to see what is in your wardrobe. Lots of green?
Ash blonde is really you, Jane. The variation of blonde you want to try sounds like a good plan.
Most important, ask your professional at the hair salon you trust. Supermarket boxes are not the best way to go.
http://beauty.about.com/od/cutcoloradvice/a/pickcolor.htm
If you see the dark haired lady shown at the very top left, you see an example of notching or point cutting the hair. See how her hair curls into the chin. Notching and layering looks great on someone with an angular face like you have. You also do not have a pointy chin, so one needs to be careful.
http://www.hair-styles-secrets-revealed.com/hair/554/how-to-thin-hair-with-scissors/
You need something to highlight your eyes and cheekbones.
You can discuss this with your hairstylist.
Myself I like, ash with streaks or layers of darker blonde and auburn, some notching, as well as curls. Curls give elegance and a look of confidence.
I saw a pic of you in another thread. Your hair was fine, blonde, soft. It looked wonderful.
You can not change your hair style or colour without changes in your wardrobe.