XML sitemaps are especially useful because it lists your site’s most important pages, allowing the search engine to crawl them all and increase understanding on your website’s structure. Webmasters use the XML Sitemap to highlight the pages on their sites that are available for crawling. This XML file lists URLs together with additional meta-data about each of these links.
Anjali, I think you should start with the Keyword Planner from Google. As a free option it is one of the best. SEMRush is great but you need to pay for it to be really effective. After GKP (Google Keyword Planner) I would also take a look at the other, more unknown suggestions Ankit talked about like KWFinder or Keyword Eye – they are quite good and will sometimes reveal keywords you wouldn’t find otherwise (for free).
You can also indicate which pages don't need to be crawled or are not important. You call the Googlebot to crawl and index your site from inside the Google Search Console. However, do note that although Google "looks" at your sitemap - Google is more interested in doing a raw crawl of your site - jumping from one link to another to spider all the pages in its database. By doing that, it also forms a link map of your site into its own index - which tell it which pages on your site are the most important pages (they are the ones that have the most links - the most prominent links).
To use this feature, click on the second tab that you will find on the top right bar. Type in the keywords that you want to view the performance of, and also type in the name of your domain. Hit the search button and allow the software to find whatever you are looking for. Site rank will analyze the top page of Yahoo, Google, and Bing to find where your site could be. Jaaxy will also show you how your post or page is performing, so you will know if it is climbing or dropping in the search.