How I mark Initiative

I use a simple system for combat, each player chooses a coloured 3 by 5 index card, I have nine colours to pick from.

I then took 15+ index cards and cut them into three 1 inch by 5 inches strips, these are for marking effects/affects in game.

I fold them in half & tent the index cards on my DM screen, I do the same with my 1 by 5 strip's and write down affects/effects on going in the game.
I use white index cards for monsters.
With this I use it for Initiative, concentration, grappled, bless, etc.....

Below are pictures of how I do this.  

Then when condition that are needed to be marked I can place the strips across the corresponding characters or monsters.

I go left to right on my DM's/GM's screen for initiative.

On the green index card is a yellow strip that says concentration
on the orange index card is a green strip that says dodge
on the yellow index card is a blue strip that says prone
on the red index card is a pink strip that says grappled.

The mini-refrigerator in the back ground has characters that have been killed in past games.