C-l clears the screen content (equivalent to the command : clear).
Shift+up go up
C-i <TAB>
C-d delete or logout
C-a goto beginning
C-e goto end

change user

[root@dhcp17 ~]# su peter
[peter@dhcp17 root]$ pwd
/root
[peter@dhcp17 root]$ cd
[peter@dhcp17 ~]$ pwd
/home/peter

time

[root@dhcp25 axtu]# time rpm -qa>/dev/null

real    0m0.700s
user    0m0.616s
sys     0m0.072s
[root@dhcp25 axtu]#