Which guide are you using for your CCNA preparation? I will compare the famous book by Mr. Todd Lammle with Mr. Richard Deal. Everyone suggests Todd lammle for sure and I think it depends how far one can absolutely love it. I did not like it as much as everyone else.

Well here are the things you should know about Todd's guide:

1.He talks about stuff you might have never heard of, yet he promises to tell you about it later in the book  and he tells that in a friendly way, this is frustrating.
2.The book covers over and above CCNA objectives, its good in a way but if our priority is becoming CCNA, those extra topics would kill your time.
3.His style of teaching is OK but not so good on few topics, actually waste of time and energy.
4.For configurations the book rocks, thats for sure. He uses a topology throughout the guide and implements different configurations like RIP, Eigrp, OSPF, interface configurations, IOS etc etc.
5.The book doesn't cover wireless topic effectively, you might get 3 or 4 questions from wireless in the test.
6.Whats beyond CCNA in this book: CNA for switches, IP telephone configs etc. If you've decided to use Todd Lammle's book, its very important to check his website for updates - www.lammle.com

What about Mr. Richard Deal's guide for CCNA?

1.The book is not so famous as Todd's but absolutely rocks!!!
2.You'd just read it like a story, yet the guide does not use informal way of explaining.
3.This guide is near to perfection, starts from the very basics of what a "network" is. So if you're completely new to networking, you will definitely appreciate this guide.
4.There are "Exam Watch" notes in between and they're direct questions from CCNA.
5.You complete a chapter, complete the "inside exam" section and take the "two minute drill"and then take the test, you will nail the subject and will not forget.
6.Configurations are not as good as Todd's but definitely NOT bad.

What now?
If you're confused which one to go for, go for Richard Deal, you won't regret it and if you have enough time you can through the configurations from Todd's guide. Like, after you're done with RIP, EIGRP, you take a look at the configuration section in Todd's guide. But this is redundant cos your labs are already covered in Richard's guide. And use GNS3 for your lab practice.

If you want to do a mixed study from both guides, you might wanna study these topics from Richard's guide for sure to be on safe side:

• Layer 2 Technologies (all about cables and layer 2 protocols)
• VLANs and Trunks(dot1q, ISL, EtherChannel etc)
• Switches and Redundancy (STP, PVSTP+, RSTP etc)
• WAN - Frame Relay, VPN
• IPV6
• NAT
• Wireless

Reminding again, the 'Exam Watch' notes in Richard's guide are answers to direct questions from CCNA.
And for the rest Todd's guide did pretty good including:

• OSI Model but take a look at Richard's on Data Link Layer (LLC and MAC) 
• Subnetting, VLSM, troubleshooting TCP/IP
• IOS and SDM
• Managing Cisco Internetwork 
• IP Routing - RIP, EIGRP, OSPF
• Security