Today I have cleared Salesforce Administrator Certification (ADM 201).

If you are also planning to do the same, I would suggest you to download the study guide from here and follow the same. Find each and every topic on Salesforce Help and watch salesforce training videos.
Secondly, set up an Admin Playground or a Developer Edition org and try it out. You will learn how these features work much better that way. You can also learn about Salesforce features using Trailhead.
Thirdly, I would recommend to focus all your effort for the next few days on Relationship types in Salesforce, Workflow Rule considerations and Sharing/Security in Salesforce. These topics will cover almost 50% of the exam questions.
Don’t miss to watch the video series Who Sees What
Tips:
- Read every topics of Study Guide minutely from Salesforce help & training.
- Follow the study guide, it’s quite enough.
- If you don’t know the right answer, no worries; search for the wrong one, it will clear off your confusion.
- Practice these things in Trailhead. It is the best way for preparation of the certification exams. Keep trailing.
Wish you Good Luck!