I have just completed semester 4 of the CCNA course. My next step is to take the actual exam - but thought I would share a few tips with anyone who are still taking their course or are about to start.
DO CASE STUDIES At the end of the semester you are expected to hand in your case study. You can reach the case study by selecting this from the pulldown-menu on the cisco.netacad.net website - it is at the bottom of the menu, where you can reach the materials for each semester.
So - when you start the semester also start looking at the case study. It is structured in such a way that you can start after having done just the first module of the semester. Do NOT wait until the end of the semester - it can be a lot of work.
I would recommend you really focus on the case studies for CCNA 3 and 4. For example, the case study in Semester 4 covers Frame Relay, OSPF, access lists, subnetting and switching. All important subjects which will give you a thorough preparation for the "real" exam.
MAKE NOTES Make notes as you go through each module. They will become vital when you want to revise later on. Also make notes after you have taken each module exam and semester exam.
ENABLE FEEDBACK - IF POSSIBLE Ask your instructor to enable feedback on your exams. That way you can go back and check your answers. This is important so that you can identify subjects you may not fully understand.
BUY THE BOOKS Although the materials on the netacad website are fantastic they do not always tell you enough. So - buy the Companion Guide which is very in-depth. A combination of the two will give you a really good understanding.
DO THE CCNA QUIZZES ON QUIA Before you attempt a module exam or semester exam, do the quia quizzes. These are often very similar to the questions on the exam and you can learn a lot.
E-LABS ARE GOOD PRACTICE You may have noticed the e-labs dotted around some of the modules? These are flash-based practicals that are very good configuration exercises. You can go through them as many times as you like, and you do not need any special equipment. Do them from home - after you have done some of them 5-6 times you will have learned the commands by rote.
GET LOTS OF LAB TIME If your college has a lab, use it. Practice cabling and configuration until you die. It is really important and will improve your understanding. If you do not have access to a lab, buy some routers and a switch
2nd hand. You can also buy a simulator, which is the next best thing.GOOD LUCK...