I did my cars piece at a time whenever I have the $ and the parts are on sale.
I'm not familiar with Euro cars, but if you going for looks, maybe you can start with lowering springs? You will prolly sacrifice ride though then you can add matching shocks later. If you want more, add anti-roll/sway bars later if you want to cut corners.
I went with non-coilovers, springs/dampers because of cost and simplicity, for Rustangs about 1/2 price. I installed them myself after watching youtube vids, forums, and reading installation sheets.
There are really many many different approaches to upgrading your suspension. Ultimately, if you have the $$$, take it to a shop, and get it over with.