I took your advice for the monsters, and I am pleased to tell you that it's working. Thanks for the advice. :) My monsters are now all at 10 hearts and I filled up my barn. The friendship levels of my newest additions are rising at one heart a day, which is fantastic.
Thanks for your advice and continue keeping up the good work. I am a big fan of your Harvest Moon guides and I think they're the best and most comprehensive guides out there.
(My advice was to increase Skill Levels with the Brush to be able to raise Monster heart levels faster.)