Misc - How To Tell What Key A Song Is In Chords & Tabs

Hi, This is my first of many posts on music theory. I have taken 
classes and all that good stuff so this lesson will be one of the
easier ones.

first the key signatures
C=0 #'s
G=1#
D=2#
A=3#
E=4#
B=5#
F#=6
C#=7#

The flat key signatures
F=1b
Bb=2b
Eb=3b
Ab=4b
Db=5b
Gb=6b
Cb=7b

Minor keys (the flat ones)
A=0b
D=1b
G=2b
C=3b
F=4b
Bb=5b
Eb=6b
Ab=7b
[ Tab from: https://www.guitartabs.cc/tabs/m/misc/how_to_tell_what_key_a_song_is_in_tab.html ]
Now the sharp ones
A=0#
E=1#
B=2#
F#=3#
C#=4#
G#=5#
D#=6#
A#=7#
now you have to know the scales those will come up later but here
is what you came here for.
More often then not the last chord of the song is what key it is in
for example [a D major chord ending the song means it is in the key of
D major (2#'s)] Sometimes the key can be determined by the first chord
unless they use an odd "leading tone"(those will come up later in
theory). Well the only other thing is if it ends on a 7th chord or 
another odd chord take out the number and put in major that usually
works. Well i will be posting more about what all of yu want to know
HOW TO IMPROVISE!!!!!!!!!!!!

Dan Bergeron