The following list presents the overall steps you need to consider and perform to create distributions with smaller root filesystems, achieve faster boot times, maintain your critical functionality, and avoid initial RAM disks:
Determine your goals and guiding principles.
Understand what contributes to your image size.
Reduce the size of the root filesystem.
Reduce the size of the kernel.
Eliminate packaging requirements.
Look for other ways to minimize size.
Iterate on the process.