[Question] How should I approach these keywords?

I am kinda new here on BHW. I am a content writer, but thinking to have some websites of my own, which provide me with extra revenue on the side. I am aiming for a decent revenue, and I am ready to invest money to build up to that income.

Alright, so with that backstory, I was researching some niche, and came across the following two kind of keywords:

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KEYWORD | Searches | Compt. | Sugg. Bid | Ad. Imp. | Exact Comp. |
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PREFIX SUFFIX | 70 | Medium | Rs. xx.xx | 0% | 92,xxx |
PREFIX WORD1 SUFFIX | 4,400 | Low | Rs.3xx.xx | 0% | 9,xxx |
PREFIX WORD2 SUFFIX | 3,600 | Low | Rs.1xx.xx | 0% | 23,xxx |
PREFIX WORD3 SUFFIX | 2,400 | Low | Rs.1xx.xx | 0% | 1,xxx |
.... and around 10 more keywords in this group ...
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KEYWORD | Searches | Compt. | Sugg. Bid | Ad. Imp. | Exact Comp. |
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KEYWORD1 | 4,400 | Low | Rs.2xx.xx | 0% | 22,xxx |
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The searches mentioned above are monthly US searches. Exact competition is obtained via Google by searching for keywords after putting them in double quotes. Conversion rate: 1 USD = ~60 Rs.

So, what do you think guys what should I target first? This is my first attempt, and I do not want to waste keywords (as it seems to me, they are good). Also, if targeting the first group of keywords, what would be a good URL structure (SEO wise):

1. prefix-suffix.tld/word (category per keyword on a single domain)
2. word.prefix-suffix.tld (subdomain per keyword)
3. prefix-word-suffix.tld (several domain names for each keyword)

Guys, any help or pointers on this?

Well. Your thread has caught my eye because I had the same problem of not being able to decide wgich one (out of these three options) to choose. I tried googling and have found very insightful info that has helped me to make a decision in favor of Subfolders. The future shows whether I has been right. Enjoy reading and good luck!!!

www(dot)webseoanalytics(dot)com/blog/multiple-domains-vs-subdomains-vs-folders-in-seo/
www(dot)searchmarketingstandard(dot)com/when-to-use-subdomains-vs-subfolders
www(dot)ameravant(dot)com/article/3398-subdomains-and-seo-pros-and-cons-of-subdomains-vs-subdirectories
www(dot)seobook(dot)com/subdomains-google-panda
www(dot)netmechanic(dot)com/news/vol6/promo_no3.htm
www(dot)site-ninja(dot)com/article/233-subdomains-and-seo-pros-and-cons-of-subdomains-vs-subdirectories