#Both are the same
:g/pattern/s/ORIGPATTERN/NEWPATTERN/g
:g/pattern/s//NEWPATTERN/g

#change delimiter to @ so you can do dirs w/o having to backslash the slashes
#from
:g/\/some\/dir/s//\/new\/dir/g
#to
:g@/some/dir@s@@/new/dir@g

#
# I use marks of 'm' and 'n' normally, since right at the m (mark) key
# I also use 'a' and 'b' when I need more ranges, x & y would work well too
# whatever system you want, just come up with one so you can easily remember them

#set a mark of 'm'
mm

#goto a mark of 'm'
'm

#from mark 'm' to mark 'n', insert a TAB at BOLD
'm,'ns/^/^I&/

#write mark range
:'m,'n w myfile

#delete from current line to mark 'm'
d'm