You can have up to 30 games/features saved in your Favourites, so I thought I'd share what I've found gives the best rewards (either to add to collections or resell) over time for anyone struggling to get a good process down. To favorite a game, hover over it in the Games list and click on the star icon. To remove that favorite, visit the Favourites star icon at the top and then click on that same game's star when you hover over it. Then, you can check the Favourites page periodically and click on "Hide Unavailable" to get a quick list of what you can do in that moment.

All of these are free unless otherwise indicated!

[ - - - Features Games - - - ]

1. Ant Hill (once per day)
www.marapets.com

2. Archeology (every 24 hours)
www.marapets.com

3. Christmas Tree (once per day)
www.marapets.com

4. Clock Tower (every 24 hours)
www.marapets.com

5. Clothing Rack (once per day)
www.marapets.com

6. Genie (once per day, 4th wish resets the count)
www.marapets.com

7. Giveaways (once per hour if you have less than 1mil MP, otherwise once every 2 hours)
www.marapets.com

8. Grave Robbing (every 3 hours when asleep)
www.marapets.com

9. Guillotine (every 16 hours, may turn your pet Headless so if you don't want that result, only put a pet in who can't be costumed Headless)
www.marapets.com

10. Nutty Tree (every 4 hours)
www.marapets.com

11. Operations Portal (once per day, may change species or costume)
www.marapets.com

12. Plushie Machine (every 15 minutes)
www.marapets.com

13. Photo Parlour (costs 1,500 MP every 12 hours and photos can make a good profit, so might not always need to do if you already have all your pets' photos collected/ to sell)
www.marapets.com

14. Pot of Gold (once per hour if you have less than 1mil MP, otherwise once every 2 hours)
www.marapets.com

15. Sewage (every 24 hours)
www.marapets.com

16. Simerian Statue (every 5 hours)
www.marapets.com

17. Test Your Strength (every 3 hours)
www.marapets.com

18. Undying Fairy (every 3 hours)
www.marapets.com

19. Worm Digging (every 3 hours)
www.marapets.com

[ - - - Chance Games - - - ]

20. Eleka Tombola (every 8 hours)
www.marapets.com

21. Fruit Machine (every 24 hours)
www.marapets.com

22. Lush Tombola (every 8 hours)
www.marapets.com

23. Open Graves (once per day)
www.marapets.com

24. Pixie Dice (costs 1,000 MP every 16 hours)
www.marapets.com

25. Prize Drop (every 16 hours)
www.marapets.com

25. Tombola (every 8 hours)
www.marapets.com

26. Trash Heap (every 48 hours)
www.marapets.com

27. Undying Tombola (every 8 hours)
www.marapets.com

28. Wheel of Fortune (costs 10,000 MP every 16 hours)
www.marapets.com

29. Windmill (once per day)
www.marapets.com

This leaves the 30th Favourites spot for any other feature/game of your choice!