When preparing to use Kali Linux in the field, you must first ensure you have a clean, working installation. A common mistake that many novice security professionals make is using a single installation across multiple assessments. This is a problem for two primary reasons:
Over the course of an assessment, you will often manually install, tweak, or otherwise change your system. These one-off changes may get you up and running quickly or solve a particular problem, but they are difficult to keep track of; they make your system more difficult to maintain; and they complicate future configurations.
Each security assessment is unique. Leaving behind notes, code, and other changes can lead to confusion, or worse — cross-contamination of client data.
That is why starting with a clean Kali installation is highly recommended and why having a pre-customized version of Kali Linux that is ready for automated installation quickly pays off. Be sure to refer back to Section 9.3, "Building Custom Kali Live ISO Images" and Section 4.3, "Unattended Installations" on how to do this, since the more you automate today, the less time you waste tomorrow.
Everyone has different requirements when it comes to how they like Kali Linux configured when they are in the field, but there are some universal recommendations that you really want to follow. First, consider using an encrypted installation as documented in Section 4.2.2, "Installation on a Fully Encrypted File System". This will protect your data on the physical machine, which is a life-saver if your laptop is ever stolen.
For extra safety during travel, you might want to nuke the decryption key (see Adding a Nuke Password for Extra Safety) after having sent an (encrypted) copy of the key to a co-worker in the office. That way, your data are secure until you get back to the office where you can restore the laptop with the decryption key.
Another item that you should double-check is the list of packages that you have installed. Consider what tools you might need for the work you are setting out to accomplish. For example, if you are embarking on a wireless security assessment, you may consider installing the kali-tools-wireless metapackage, which contains all of the wireless assessment tools available in Kali Linux, or if a web application assessment is coming up, you can install all of the available web application testing tools with the kali-tools-web metapackage. It is best to assume that you will not have easy access to the Internet while conducting a security assessment, so be sure to prepare as much as possible in advance.
For the same reason, you might want to review your network settings (see Section 5.1, "Configuring the Network" and Section 7.3, "Securing Network Services"). Double-check your DHCP settings and review the services that are listening on your assigned IP address. These settings might make a critical impact to your success. You can't assess what you can't see and excessive listening services might flag your system and get you shut down before you get started.
If your role involves investigating network intrusions, paying close attention to your network settings is even more important and you need to avoid altering the impacted systems. A customized version of Kali with the kali-tools-forensic metapackage booted up in forensics mode will not automatically mount disks or use a swap partition. In this way, you can help maintain the integrity of the system under analysis while making use of the many forensics tools available in Kali Linux.
It is critical that you properly prepare your Kali Linux installation for the job. You will find that a clean, efficient, and effective Kali environment will always make everything that follows much smoother.