I want a/an ............ 〜〜〜がほしい。 I want a dog. I want more free time. I want a better body. I want a boy/girlfriend. I want a better salary.
I want to.......... 〜〜〜をしたい。 I want to lose weight. I want to sleep late. I want to go home early. I want to go to Tahiti. I want to learn English.
I want you/him/her/them/it to......... 〜〜〜をしてほしい。 I want my boyfriend to take me to Tahiti. I want my boss to be nicer to me. I want my dog to do tricks. I want you to stay. I want you to relax.