That used to be me. I'd suggest you stay away from floaty tops and dresses with no waist definition, they made me look pregnant. But waistcoats over shirts work well with either skinny jeans or skirts with thick tights. Stick to browns and it'll go down a treat.
Can't comment on the shape issue, coz I ain't never been a size 6/8!!! However, I have the same colouring and find that autumnal tones work really well - greens and rusty oranges etc. I also look good in rich mauves too. Generally I'd avoid anything wishy-washy like pale pink or cream, as those shades will sap the colour out of your skin.
If you are having problems getting clothes that are bisty enough for you, but slim enough for your small frame, then have a look at Bravissimo (Google them; they have a website and real shops). They sell women's clothes in dress sizes and three sizes of "Curviness".