I am new to apex, and want to learn from scratch. What could be the best practice for that?

Hi @Hitesh Sharma, If you are already good in other coding, apex is not tough to learn on your end. You just start with the basics and learn one by one that I mentioned below,  

1. Go with the bascis of Apex in salesforce 

2. Do some handson using the Apex like palindrome kind of excersices and understand the coding. 

3. Next go with Triggers, Async Apex concepts, test classes. 

4. Use trailhead for the learning and get handson from AI, do your practices. For the trailhead learning, you just go with the Developer Beginner trailmix that shared in previous comment. 

If you are dedicately looking apex, you can learn within 45 days with good understanding. There are lot of materials there in Salesforce help document as well as other forums. 

Basically, learning apex is not hard and you just start your learning. Hope this info is enough to start your learning. If any doubts, ask here, I am ready to help you.