Extraction describes material from roasted coffee dissolving into the brewing water. It is different from strength: a cup can be concentrated without having the flavor balance you want. That distinction makes troubleshooting more useful than simply asking whether a coffee tastes strong.
Record dose, water quantity, grind and the relevant brewing time. Begin with clean equipment and coffee appropriate to the method. If you change several factors at once, an improvement may be difficult to reproduce because its cause is unclear.
Choose one adjustment based on the particular complaint and compare it with the starting recipe. Judge the result after it has cooled enough to taste comfortably. A process measurement can help explain a change, but it does not replace assessing sweetness, acidity, bitterness and texture in the actual drink.
The conversation
A good question can make a better brew.