Various things you may wish to configure to optimize use of flash storage, such as CompactFlash card, MMC/SD card, or Solid State Drive (SSD), include:

Inform flash controller it can reclaim sectors

This is done by specifying the discard option in fstab. Recognizing this option is dependent on the file system. Ext4 and BTrFS recognize and use this option.

Finding recently changed files

Finding out which files have been written to recently:

sudo find / -xdev -printf '%T+ %P\n' | sort -n | tail -99

syslog

Edit /etc/rsyslog.conf and comment out any log files that are not required.

/var/run and /var/lock

sudoedit /etc/default/rcS

..then edit these lines:

RAMRUN=yes
RAMLOCK=yes

..so that /var/run and /var/lock are mounted in RAM.