How to mix instant coffee?

I can't start my day without drinking a cup of coffee. Coffee shops are in abundance but when I want to make one at home, I always end up using 3-in-1 variants. We have coffee (instant only. I'll try brewing when I get my own coffeemaker) at home, creamer/milk, and sugar but why 3-in-1? Because I dunno how to mix the right amounts to make my own cup. Too sweet. Too strong. Too much creamer/milk. It ends with such a waste... At least with 3-in-1 I just have to pour hot water. Still, I'd like to learn how to mix appropriate amounts of each ingredients 'coz there are times I run out of 3-in-1 sachets.

Suggestions will be very much appreciated. hehe...