I recently took the A28 exam from Citrix and wish to share my tips and my experience with this exam.
Now to compare with the 9.2 exam this was A LOT more difficult. Have to say that Citrix has really created a challenging exam which focused a lot on most of the different functions within Netscaler.
There werent so many CLI commands (Which I felt the 9.2 exam was) but more about how to think “when do I use this function over that function”
For my part I have worked with the product some time now and I have taken a traning course on the older version. The best part is the study guide that Citrix offers on their web site.
Which can be found here –> training.citrix.com/mod/ctxcatalog/course.php?id=511
The study guide shows on what areas you will be tested, and on what area you need to know “HOW” which is the most typical case for CLI commands 
and “WHEN” is mostly when to use one function or another.
But you should remember most of the cli commands assosiated with each of the focus areas in the study guide.
So my top tips!
* Troubleshooting commands
* SSL (ciphers, converting, importing, binding)
* Load balancing (monitoring, persistency)
* VLANs, IP config and interface configuration
* Link-load balancing
* Use the study guide! and eDocs!
Here are the other points from the study guide how to configure the different parts can be found on eDocs
Citrix eDocs:
? Forcing the Primary Node to Stay Primary
? Forcing the Secondary Node to Stay
Secondary
? Configuring High Availability Nodes in
Different Subnets
? Configuring the Communication Intervals
? Configuring Fail-Safe Mode
? Configuring Users and Groups
? Creating or Modifying a VLAN
? Configuring VLANs on a Single Subnet
? Configuring Multiple Untagged VLANS
? across Multiple Subnets
? Synchronizing Configuration Files in a
High Availability Setup
? Monitoring the Extended ACL
? Renumbering the priority of Extended
ACLs
? Choosing and Configuring Persistence
Settings
? Viewing Persistence Sessions
? Configuring Persistence Groups
? Configuring Load Balancing in Direct
Server Return Mode
? Configuring a Backup Load Balancing
Virtual Server
? Redirecting Client Requests to an Alternate
URL
? Configuring Access Gateway Settings with
the Remote Access Wizard
? Converting the Format of SSL Certificates
for Import or Export
? Specifying a TCP Buffer Size
? Configuring TCP Window Scaling
? Configuring TCP Profiles
? How the Integrated Cache Works
? Improving Cache Performance
? Monitoring TCP-based Applications
? Configuring Call Home
? Generating the Tar Archive of
Configuration Data of NetScaler Devices