The best thing to do to increase friendship and to most likely get gifts back is to send gifts!
Here are a list of things you can send:
Special Gifts[]
These are all unlimited gifts Valentines Gifts
 Be Mine Giftbox |
 Hugs'n Kisses Giftbox |
 With Love Giftbox |
 Sweetheart Giftbox |
 Cupids Giftbox |
Collectibles[]
These gifts are items you own! So be careful what you give and who to!
 Pear Tree |
 Topiary |
 Topiary |
 Oak Tree |
 Red Oak Tree |
 Maple Tree |
Animals[]
All the animals in the game are available to give as a gift but some of them are not unlimited gifts and some are one's that you own!
To view the all the animals click here