Poker Notation
When I study hands, I usually like to write them down using notation that is easy to understand and conveys as much information as possible while keeping it compact. Here's an example of some hands played by Davidi Kitai, a professional Belgian poker player, that I looked at awhile back.

Let's examine the first hand, which occupy the first four rows of this page, which is as follows:
6 |
U |
A |
c |
3 |
c |
U |
2 |
T |
6.5 |
U |
6.5 |
|
16 |
A |
d |
7 |
s |
2 |
d |
T |
6 |
U |
6 |
|
|
|
28 |
|
|
|
|
4 |
h |
|
|
|
|
|
|
|
|
|
|
|
|
Q |
c |
U |
6 |
T |
6 |
|
|
|
40 |
First row: we see that our hero Davidi is on Seat 6 and is Under the Gun (U) holding Ace of clubs and 3 of clubs. He opens with 2 blinds and the button (our villian) 3-bets to 6.5 blinds and then calls, which means that the pot is now at 16 big blinds (adding up the antes).
Second row: the flop comes Ace of diamonds, 7 of spades, and 2 of diamonds. Notice that Davidi is first to act and checks to the button who bets 6 BB. Davidi just calls, increasing the total pot size to 28 BB.
Third row: The turn is a 4 of hearts. Both players check.
Fourth row: The river is a Queen of clubs. Davidi bets out 6 BB and the Button calls. At showdown, Davidi wins this hand, which is indicated by the circle over the U. Notice that because the Villian did not show their hand, it is not written here.
As you could tell, the left side is for the hand that you have and the cards that are shown on the flop, turn, and river. The right side is for recording the betting action from all of the players involved. If the right hand side is completely blank, you know immediately that all players checked their hand. I always use blinds as the unit amount because amounts can change throughout a tournament, although for cash game, you could instead write down the exact cash value. Here is the list of abbreviations for each position:
U - under the gun
M - under the gun + 1
E - under the gun + 2
L - lojack
H - hijack
C - cutoff
T - button
S - small blind
B - big blind
Obviously there is other useful information that you might want to capture, such as whether some one took a long time to make a decision, effective stack size(s), level blinds, how far you're from the bubble, etc. But I think for the most poker players, what they care most about are: (1) position, (2) betting action, (3) cards on the table, and (4) pot size. This notation has worked for me and maybe it'll also work for you too.