Don't use any stopwords in your meta description.
You can find the Google stopwords here: http://www.link-assistant.com/seo-stop-words.html
I want to know that after doing keyword research how to choose keyword phrase to make meta title and meta description tags? All experts, Please share your knowledge.
It depend which market you want to reach then you choose the keyword they mostly search for.
High monthly search keywords does not mean the best keywords too choose because of high competitor.
You may narrow or choose niche keywords and identify which is better to give higher conversion rate.
Such as domain may not the 1st choice while you target domain name registration , the search is lower but yet high conversion rate compare to target domain keyword.