I thought I'd share some thoughts I have for getting the economy of your pet shop going smoothly and profitably... I'm at level 42 now and wish I had looked into it sooner, but here are some suggestions new players might find useful:
Pets: Regardless of the specialization of your shop, to get more income you need pets with high ROI - return on investment. ROI is an econimics term that shows how long it will take to get back the money you invested. For example, if you pay 3000 coins for a pet that pays 50 coins per day, it will take 60 days to get your original investment back and start earning profit. Same applies to breeding and upgrades: one can easily calculate the time it takes to break even. You want the pets/upgrades that have the fastest ROI. This strategy depends on how often you collect from your pets: if you do it once a day, the pet that suppose to bring you 100 coins in 4 hours will earn you only 100 coins a day instead of say 400 if you collect frequently. So ROI does depend on your play style. In any case, there are 3 pets I recommend for getting good ROI regardless of what your shop preference is (mine is mostly cats): English Mastiff, Wallaroo, and Brussels Griffon. They work well if you collect 3-4 times a day.
Daily bonus: This is important in the early levels. Later in the game it is only a small portion of your economy. To get good bonus multiplyer make sure your ratings for decoration, number of baby pets( nursery), shop size, and pet variety are 5 or at least 4. These are not very hard to maintain, but will give you noticable income boost at early levels.
Hope this helps...