I would upgrade from the Mer first of all to be honest.
Depending on what shape the paintwork is in swirl and defect wise and your working by hand the car may benifit from a a going over with Meguiars Scratch X. Alternatively you could just use it in spot areas as and where needed.
After that or straight away if you don't feel it needs any of the above I would tend to use Autoglym Super Resin Polish rather than the Mer. Worked correctly applying a small amount to each panel and working it till it is nearly all gone you should get great results. The first time you use it 2 applications sometimes produce better results.
This leaves a perfect base for the Autoglym Extra Gloss Protection. This will add the the depth and gloss slightly aswell as leave a good level of protection to the polished paintwork. 2 or 3 layers over a few weeks will give maximum loooks and a good few months protection.
Both the above can be sourced cheaply from Halfords, not sure what budget you working to but if you want to gain the last possible bits of the look have a look into a nice Carnuba wax, I like P21s Carnuba on Blues.
The main bulk of the look you trying to create and all the hard work is in the polishing stages so spend some decent time in the prep. Don't forget to clay the car first of all if there is contamination on there washing alone is not removing.
Hope this helps.
Rich
