How can I get good grades in Cisco 100–105?

I would say you should keep practicing because whatever you read is not sufficient you might have heard that “Practice makes a man perfect”. Apart from that, you should do the following things

1. Buy books published by cisco press, they are extremely useful but if you choose the first option you will get cisco press books from the academy itself.
2. Browse for CCENT online study guides and have a look at that because it will help you in quick review of concepts
3. Signup for online classes and watch videos on youtube
4. Start reading all topics according to syllabus with practical. Because practical is also important for the exam.
5. As I suggested practice the exam questions here is my suggestion CCENT (ICND1) 100–105 Practice Tests
6. Download and Install Mobile apps to practice so that you can practice anywhere. check out the Android app for ccent certification and also check the iOS app for ccent practice
7. Join study groups in facebook, Reddit and other social media groups so that you can share and gain your knowledge
8. And when you have the confidence that you can pass the exam, go and give the exam…

All The Best!

Thanks