Moving to Honolulu alone

Hey! Im an european looking to move to Hawaii next year (I'll be 18yo) . I read that it's very expensive and choosing the island correctly is very important in order to not feel isolated and apparently the Oahu island is the one that corresponds most to young people.
I was wondering, is it easy to make friends in Hawaii? and where is the best place to meet them? Which are the 'trendy' places? Is Hawaii accepting of foreigners? Is there flat sharing in Honolulu? Is it easy to find jobs in hotels or restaurants?
Feel free to leave any further info !