Player notes (like on PokerStars)

How do you use them?

When do you add them? After a particularly telling hand, or do you wait until you have a larger sample size of hands to draw a conclusion about a player?

And how much do you trust them? Do you find yourself having to revise them when a player doesn't seem to be following "the script" you have for them?

I'm starting to dabble with them, and it seems as if they could be useful tools if done right.

Keeping notes on a player can be very valuable.
Especially if you are always playing the same games day after day.

If you get beat in a hand by someone just luck-boxing on you, make a note.
If you see a player consistently making the same move time and time again,
always defending their SB, making the standard raise every time they are on the button,
make a note

If you have a HUD going you can decide after a session to go back and look
at various players actions. You just might pick up some tells.
If you have one player who you just CAN'T beat, go over the hands played against them.
Did you play too aggressive and not see them showing strength?
Did you allow them to get to a winning hand on the river by trying to trap?

Then the next time you see them you will at least have some idea of their style.

Use the color coding on PS or FTP to identify the fishes, the sharks,
the loose and the passive player.
Pick one color to represent friends and one to mark the villains
but don't allow these notes to become a 'Bible' on how to play.

Notes are just another piece of information.

As far as how much should you trust them, it will depend on how much you trust your reads. If you see a BvB situation, and you see the SB pushing wide into the BB, try to see why. Is the SB just a maniac? Is the BB real tight and SB is abusing this? Whatever reason, make a note of it. If you see the same player only pushing tight in another game against a real loose BB, then you know the SB is a player who will adjust to different player types.

This is just one way notes can help you. If you use a HUD, you can often compare your notes to HUD stats.

Notes will be very helpful if you play a lot at the same stakes. You will eventually meet the rags again, and having a little info never hurts.

Dating notes is good too, as a player may play a lot better in a few months time.

make the notes and let incorporate them into your decision how to play against him. Call a raise, raise him, call AI etc.

I find noting stakes and/or game type helps. Your note at 10nl might not apply if you meet the player in a sng or a higher limit. I also like to note multi-tablers.

I always use notes if I noticed some particular habit/action/tell on my opponents. So I'll know next time when I play against them what type of move they're doing and with what particular hand.

I don't use the color coding but I think I'm gonna start doing it to select all the types of players