For concept building don't start with DC pandey you can start your preparation by HC Verma.

Several solved problems are solved incorrectly whereas others use non-conventional and lengthy methods.

After, building your base strong you can move to DC Pandey to solve more questions. D C Pandey has a huge question bank which can polish your problem solving speed and accuracy.

Solving HC Verma and DC Pandey will help you to clear JEE Main exam. 

Good Luck!!