I personally think that POV has a great deal to do with setting the mood, tone, atmosphere, and feel of the story. If you want an introspective piece, 1st person often works best, though if you want the 'feel' of it to be a bit more reserved, you'd want to pick 3rd person but keep it all through one character's view. Also, when switching POV, you can oftentimes sneak in subtle nods or foreshadowings by allowing the current character POV to be a bit more objective. So, then, I always try to decide what feel I want for my story before I decide on POV.
In 'And Then There Was Light' (and
to the compliment, Virginia), I chose 1st person Lois because I wanted to draw out the mystery and obviously seeing through Clark's view would have cut that real short real fast. However, in 'Lethal Qualities,' I was (hopefully) able to keep some suspense going by switching between Clark, Lois, and Perry's point of view every rotating three chapters. 'Me, Myself, And You' was 1st person Clark and referred to Lois as 'you' so that it ideally felt like the reader was inside Clark's head. Each time, the POV was chosen because of the feel of the story.
Sometimes, I have to admit, that if the story focuses more on the plot, POV don't figure in as heavily, but certainly in the shorter stories they do, such as in mozartmaid's 'Frigid' or in Deadly Chakram's 'Just Say My Name...' stories, as well as Lynn S M's 'Echolalia.'
As to keeping in character within the POV, the only advice I can give from personal experience is to believe everything your character does, feel everything they do, and even though you want to consider what other characters are doing so that you can keep your storyline going, always do that objectively, never personally so that you can keep in the mindset of your character.
Anyway, don't know if any of that helped (I've found it's hard to put into words my writing process--it makes perfect sense until I try to explain it), but there it is.
