Our Model Philippa usually takes a 10 in our labels. Her details:

Height : 178cm / 5ft10in

Bust: 89cm / 35in

Waist: 71cm / 28in

Hip : 96cm / 38in  

 Philippa models almost every style on our website except some denim - and we usually put her in a size 10 / S in brands like Mela Purdie, MEL, MA Dainty, Trelise Cooper.
If we size her up or down it will be noted in the product description so you can better judge the size of the garment against others you're familiar with. 
Note that the length of some items may look longer on you if you are not as tall as Philippa!
Just use Ask a Question below if you are unsure about any sizing.