The first time I played this game, I didn't really put much thinking into stratagies on gaining a high score.  I just wanted to get to the end of the game and see what upgrades there was throughout.  For those of you that have played it through once already, you would have noticed that some of your upgrades disappear when you move from London to Paris then from Paris to New York.   These upgrades do return and are still fully upgraded when they return (the glitter machine and the branding machine etc....).
 
Second time round I started to think more stratigically.  I started out by trying to better my score in the very first level.  Skipped the tutorial and served each customer one by one.  Not many points gained.  So I then served two customers thier perfumes at the same time and my score increased.  This only works on the first couple of levels, cause after that speed counts for everything.  (If you can still serve two customers at the same time quickly you get a small bonus)
 
The real score gain came when you mix your own perfumes and have upgrades for the glitter machine, then the branding machine and then the gift machine.  At first I thought that I would just mix the perfumes to keep the speed fast, but once you have the upgrades to the machines for red, yellow, and blue you really don't need the fast choice, you can mix the perfumes to gain more profit and choose average or even slow.  Then add something to every bottle you sell.  If you get the chance to do so add more then one thing.  It does not matter if the customer asks for it or not they will take it and you will get more profit.  When you get the bottled perfumes always buy as many as the most expensive ones your budget will allow (don't forget you need your upgrades)  and add as much as you can to each bottle and give the most expensive ones to customers who have the question marks above thier heads.  When you have the table in the middle always make sure that you have a fully loaded expensive bottle to give to a customer with a question mark.  That includes the glitter, branding and gift wrap (bow), so you can give them it immediately to gain the most profit.  when you have the final four customers in the shop keep everyone waiting while you fully load each of thier bottles to gain an extra boost at the end. (use the flower to keep the most impatient one/s happy)
 
You also get bonus' for serving the already bottled perfumes in a row, if you get for example six customers that want bottled perfume and one that you have to mix yourself, keep the one you have to mix for yourself waiting (get their order ready, just don't give it to them yet) and give out all of the bottled perfumes first, you will notice X1, X2, X3 etc.. as you give them to the customers.
 
Lastly, you need to be fast, speed counts for bonus tips and the faster you can get an order ready and give it to the customer the more money you will get.
 

Hello! I fugerd it out also! But I would never have explained better than you. That's the reason I didn't post this. I'm sure someone will appreciate.
If you're fast enough at every level you before you gave to the customers the perfume botles you could stick the perfumes to every machine unless the first one which is slow.
I have level 47 and 48 to improve my score. I think I could squize 5000-8000 points more.
I'm thinking...if "Perfume_of_theAmish will see this he'll tell you're a cheater lol.
Thank you for posting this, as I told I would never be able to explain this as you.