hello,

I would have answered your question much better if you have mentioned your branch for which your are preparing GATE.

Two ways of practice books: 

ONLINE , i would recommend you 

1.RavindraBabu Ravula's GATE lectures (There is also a youtube channel regarding GATE preparation lectures)they provide complete material 

2.GATE related materials from famous coaching institutions like ACE and GATE FORUM

3.Made Easy Online test series

OFFLINE ,there are n number of publications like MadeEasy,Arihant,Pathfinder Academy,Alantic Publishers,etc..

ALL the BEST :)

hope this helped you!

Regards,

SIRISHA SANATHA.

"https://engineering.careers360.com/articles/what-are-best-books-for-gate-preparation"  go throug this link their you can find the best practice books to prepare GATE for different branches.