Augmenting gravel substrate - Any tips, suggestions, things to avoid?

[WallysWorld]

Over the years I’ve vacuumed out enough of my substrate that I want to augment. I have a small bag of newly purchased sand that is similar/identical to the sand already in the tank.

Any suggestions on how to properly augment, avoiding pitfalls and mistakes?

 

[smitten with ocean life]

when ive done that i just add small amounts to the areas i need replenished. i dont mix it. just carefully put it in