Learn the basics. Before getting started in computer forensics, you need to have a foundation in what it entails.
Download forensic software and see how it works. There are many different tools available that don't cost anything; some of these can be found at Open Source Forensics. These solutions provide a perfect opportunity for someone to learn how to use different forensic software.
Create virtual machines to use as target computers when learning the software. Virtual machine software, like VirtualBox allows you to create a virtual computing environment that you can use for testing.
Locate online training. Once you have a grasp of computer forensics, it is time to take your training to the next level. There are many tutorials that can be found online that will help you better learn the different forensic software. Additionally, you can look into training packages that for a price will teach specific skills and software.
Read books on forensics. There are many different books written on the subject that cover software packages like EnCase, methodologies used in forensic cases, and certification study manuals.