Easiest chance to get this is in Normal mode. If you've played Sally Salon you already know the drill but if you haven't all you need to do is make sure every customer per 'day' in each little shop leaves the shop with a full set of love hearts.
You can repeat levels over again if you missed out on someone and often it's much easier once you've gained a few upgrades for your shop.
Just make sure in 10 levels that everyone leaves with all their hearts full and this achievement will pop after the 10th level is finished.
A tip: I'd make sure I'd have the Herbal Tea machine and upgraded to atleast two ASAP. Then when people are going to the cash register you can see if they have full hearts or not and if they don't give them a cup of tea. Make sure to have tea brewing at all times so you don't get caught out if using this tip.