There are two characters sheets: the one you use for building, and the one you use at the table. The one you use for building stays in your binder (unless you build at the table I guess?). The one you use for playing goes in front of you while you play.
Put the most important information in the upper-left or upper-right of the character sheet. Upper-left: natural scanning order for left-to-right languages. Upper-right: you can make notes near it without obscuring the rest of the sheet, for right-handed players.
The most important information is usually:
AC and other defenses
HP
and possibly things like movement speed, and certain passive skills (Insight / Perception in 4e)
The most important information is definitely not:
Your name
Your character's name (it's
your sheet, surely you remember this?)
race (ditto)
class (ditto)
level (typically irrelevant during a game)
ability scores (typically irrelevant, only their derived bonuses matter)
etc.
All this stuff goes at the bottom or on the back, if at all.
The next most important information is typically:
skill modifiers
basic attacks / most commonly used powers
In 4e you typically have separate "power cards" for your powers. These should be organized by action type (standard, move, minor, immediate) at minimum. I actually have a whole article pitch about making a grid with action types on one axis and frequency (Daily, Encounter, At-Will) on the other. Pitched to Dragon magazine during the 4e days but never picked up.
Anyway, this is still how I organize my 4e powers.
Hit Points
At low levels I've had good success tracking this with poker chips, white and red, combined total = total HP and red = bloodied HP (half of max). So I, and others, can see at a glance how my PC is doing.
Blue = temp HP.
It starts to break down when the stack of chips gets too tall.
Table Tents
If you have stuff your PC gives to others, like auras or situational buffs, put it on a table tent so others can see it. Put it on both sides of the tent so no matter where someone sit they can see it, including directly beside you.
On the tent is where you'd put something like "Dakkon Blackblade, male human fighter, 13th level" and then a character portrait or (better IMO) screengrab of the mini you're using.
Under the character name put info like, "+2 AC when adjacent to Dakkon (Made Up Shield Feat)" that affects the other players' characters.
I've probably got more tricks I don't even realize I'm doing, but that'll get you started.
