How to use 可爱，properly?
There's nothing very special about the usage of 可爱. In Chinese many 'adjectives' are formed from verbs. 

E.g. 


好吃 ("good to eat") is tasty/delicious or 
有趣 ("has interest") is interesting and
难看 ("hard to look at") is ugly. 


These are not really adjectives, but their best English counterparts are adjectives, so you can think of them as 'adjectives'. 

Similarly, 


可爱 ("can be loved") is cute/lovely.  


You can use 可爱 to describe people, especially children, or animals, and even inanimate things. 


这只狗很可爱！This dog is very cute! (可爱 is the predicate of the sentence)
可爱的小女孩 cute (little) girl (可爱 is used as an adjective to describe a noun)


In case of animals, you can also use 萌物 ("cute thing") to denote an animal that is just cute, 萌宠 is a cute pet and 卖萌 means "to act cute/behave in a cute way".