SC2Mapster

I suggest you read my bank facts thread, it also have a showcase map: http://www.sc2mapster.com/forums/resources/tutorials/28875-trigger-bank-facts

Try to learn how you save and load values from that tutorial. Ignore what you are saving there. Just imagine you are saving integer variable A and load the integer into your variable at map start.

I've my own tutorial map which was useful for others, too.
I've just included the detection of first time players.
It contains a function that copies everything except stored units from 1 bank to another.
Have fun with it.

Here you go.

I. Bank
    Events
        Game - Map initialization
    Local Variables
    Conditions
    Actions
        Bank - Preload and synchronize bank "coolbanko" for player 1
        Bank - Preload and synchronize bank "coolbanko" for player 2
        Player Group - Pick each player in (Active Players) and do (Actions)
            Actions
                Bank - Open bank "coolbanko" for player (Picked player)
                Variable - Set PlayerKills[(Picked player)] = (Load "Kills" of section "Player" from bank (Last opened bank) as integer value)
                Leaderboard - Set Leaderboard item text at column 2 and row (Picked player) to (Text(PlayerKills[(Picked player)]))

II. Kills
    Events
        Unit - Any Unit dies
    Local Variables
    Conditions
        (Killing player) != (Triggering player)
        (Player (Killing player) treats player (Triggering player) as Enemy) == True
    Actions
        Variable - Modify PlayerKills[(Killing player)]: + 1
        Leaderboard - Set Leaderboard item text at column 2 and row (Killing player) to (Text(PlayerKills[(Killing player)]))
        Bank - Open bank "coolbanko" for player (Killing player)
        Bank - Store integer PlayerKills[(Killing player)] as "Kills" of section "Player" in bank (Last opened bank)
        Bank - Save bank (Last opened bank)