A keyword with High Search Volume will convert

A keyword with High Competition will convert

A Keyword with SHort Tail Convert

A keyword with Long Tail Convert

Rule is simple

A keyword with Buying intent Convert

The short tail may be part of it

Long-tail may be part of it

For Example :

sharing from one of my campaigns

Target Country: India

Resume Writing 8100 Search Volume ( Less Conversion )

Resume Writing Services 2400 Search Volume ( High Conversion)

Using it for Paid Ads also ( Well Tested )