Don't say things like, "What do you think when...", say, "When do you think...":
When do you think you are going to be home?
When do you think he'll propose?
If you want to start with "What do you think..." and follow that up with a where or when question, make sure you include the word "about". So:
What do you think about where the best beaches in the world are?
or:
Where are the best beaches in the world?
Note: These are not necessarily the same question! Observe:
Q: Where are the best beaches in the world?
A: The best beaches in the world are in Hawaii, Sri Lanka, and Brazil.
Q: What do you think about where the best beaches in the world are?
A: I think those places tend to be too crowded, and I think the hotels there are too expensive.
Note: I could give the answer to the first question as my answer to the second question, but I could not give my answer to the second question as my answer to the first question.
Last note: I'm not going to fix these one-by-one, as that would be proofreading, and make this question off-topic.