Saying the seemingly simple sentence "What does (something) look like?" in Japanese appears to be very difficult for English-speaking Japanese-learners as far as my own experience with them goes.
The major reason for that, according to none other than my own observation, is that they will try to use a verb or verb phrase that sounds like "to look" or "to look like" and therefore, will tend to end up using 「[見]{み}える」. Unfortunately, that is a word that is not used in the natural-sounding ways to say "What does (something) look like?"
Some learners might argue that verb phrases such as 「～～ように見える」 and 「～～みたいに見える」 are often used by native speakers. They actually are, but here is the important difference. In OP's question, "What does your sister look like?" and "What does your new home look like?" clearly are questions asked by someone who has not seen the sister or the new home, respectively.
If one used 「どう見える」,「どのように見える」, etc., it would be a question asking for someone's impression or opinion of a thing that he surely has seen before or even that he is standing in front of right now.
This is why native speakers do not use 「見える」 in saying "What does your sister look like?" or "What does your new home look like?"
Natural ways to say those would be:
「お[姉]{ねえ}さん（or [妹]{いもうと}さん）って、[外見]{がいけん}はどんな[感]{かん}じなの？」
「お姉さんは[見]{み}た[目]{め}はどんな感じなんですか。」
「[新]{あたら}しいおうちってどんな[外観]{がいかん}なの？」
「新しいおうちの外観はどんな感じなんですか。」
