Here's how to do this with Ahrefs:

1. Get a list of keywords you are ranking or trying to rank for. If you don't have a way to do this, you can do it with Ahrefs. Go to Ahrefs Site Explorer, click on "SERPs Analysis" and enter your domain name. Find the top keywords you are ranking for. Enter these in Google and find out the other websites ranking for these keywords. These are most likely your competitors.

2. Enter your competitor's website url into Ahrefs. Navigate to the "External" tab. Ahrefs sorts the backlinks with the most important backlinks at the top. Look and see if you can build backlinks on these website's as well.

Good luck and hit me up if you have any questions.

You can find your top 10 competitors with a keyword with market samurai. There is a free trial version available for download.

Market Samurai is useless for backlink data.

SpyGlass will give you the most complete information.

That page ranking #1 for your keyword, that's your competition.

Use traffic travis to check competitor and SEO spyglass to check backlinks.