Hello, there !

"According to X" is synonym for "if we are to believe X". It suggests a distance between who (or what) the speaker quotes and what the speaker thinks.

ex : According to Mr Smith, this jumper is blue.
(That's what Mr Smith thinks ; but for me, it's green)

As a consequence, "according to me" suggests that the speaker quotes himself, which can only be used either ironically or if you're a conceited person, since it is synonym for something like :

"As far as I am concerned, I personally think that ... "

(strongly stressing "personally" and the first "I")