Hello,
Its difficult to explain to someone how to apply make up i think without being there!!
I agree that its good to maybe wear mascara and lipgloss, maybe a bit of blusher. Also agree about asking for some help at the beauty counter in department store. Happily help for free and its lovely!This will definitely help.
Its sounds as though you have good colouring and probably dont need much hep. You hair sounds nice too.
You sound a very different shape to me. But jeans are always a good idea, so many types. Boot cut are always flattering,. mAKE sure they are a good length as ankle swingers are most unflattering. i always buy long length jeans, unless im wearing them with trainers/flip flops, then maybe a tad shorter than with boots/heels. Baggy tops make you look bigger. If you like showing a bit of clevage then id go for more v-necked styles as they look better with bigger boobs too. Not so much black maybe? I like black too, but other darker(or lighter!) colours can still look good.
Primark sounds fine, they do some good stuff, but i wouldnt just stick to the one shop. If you are looking for clothes that arent too expensive, also try H&M, MkOne, New Look, Asda, tesco