Welcome bra,a good skimmer as sunburst said good cured live rock,aragonite seachem or the best caribsea ,a sump with a deep sand bed,a good volume return pump in your sump,very good flow in your tank,t5 lights or metal halides,and stability from seachem to kick start your tank and let it run for at least 4-6 weeks before adding any thing.
A very WARM Welcome to MASA, Pieter! Thanks for joining us! I am very glad that you found us!
A few suggestions have already been made. Very good suggestions.
Please read as much on our "New Members" threads, and any questions you might have - please post any possible decisions before you actually take action, regarding the setup of your marine tank.
As this WILL most likely save you a LOT of money, and save many a fish's life ;-)
Also - double check everything that your LFS tells you, with us, as we have encountered some dubious suggestions by LFS's in the past.