Use enough coffee!
“Waiter, if this is coffee, bring me tea. If it’s tea, bring me coffee.” Serious coffee drinkers get the joke, we’ve all been subjected to weak coffee in restaurants. It’s not the worst, I would nominate late night long ago brewed convenience store Maxwell House for that honor, but it’s pretty bad.
This is fundamental. The basic thing here is that it’s much easier to use too little coffee than to use too much. Unless you’re quite sure your coffee is strong enough, try adding a scoop more to your ground coffee and see what it’s like. Actually try adding an extra scoop anyway. My own experience of this is there’s a fairly clear point at which the resulting brew is no longer weak, then a fairly extended range where your coffee is strong enough, and finally a point at which it becomes, to some palates at least, too strong.
Tastes will certainly differ, but most people seem to agree on the lesser quality of weak coffee. I find restaurant coffee is generally on the weak side. With high quality, expensive coffee, not using enough coffee is just a waste.
I’ve recently set up a small kitchen scale right next to my grinder, and have started weighing my grounds and water. When I start to get a feel for what’s what, I’ll share my experience here.