Earning potential for an average authority site?

I have been thinking to invest money in new projects as I strongly believe in the saying "Don't put all your eggs in one basket". So, after seeing so many posts and following many methods, I conclude that the best, safe and long term (in my view) investment will be in some authority sites. I do not have much experience with authority sites so looking for some suggestions about how to start.

How much investment is required on one website?
Should I use new domain or expired ones?
How to select the topic for the site?
How do you monetize the site? Only adsense or any other also?

Looking for sincere advises and information from those who are already in this business. As much information as possible.

Thanks a lot in advance.

lol impossible to answer questions, incredibly subjective.

read threads about authority site building.

mynameisfrankenstein said:

lol impossible to answer questions, incredibly subjective.

read threads about authority site building.

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Thanks. Sure, let me search.

What is the earning potential? How long is the length of the string? Similar questions in that they are all broad and change with each string/niche.

jiungsong said:

What is the earning potential? How long is the length of the string? Similar questions in that they are all broad and change with each string/niche.

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Almost in all of the thread which I read till now, every one is saying that it is almost impossible to answer the questions. That's weird. By the way, thanks for your reply.

TomBran said:

Almost in all of the thread which I read till now, every one is saying that it is almost impossible to answer the questions. That's weird. By the way, thanks for your reply.

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Pet accessory niche sites will make less than expensive tech gear sites

jiungsong said:

Pet accessory niche sites will make less than expensive tech gear sites

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Might be easier to rank though hehe.