Let’s make an assumption that your input speed (club head speed) will not increase.
Your first target is smash factor – To improve this you want to reduce any energy loss (too much friction).
This can be done by loft adjustment, face angle, COG placement, golf shaft, angle of attack and club path changes. Once you get your energy output up (ball speed increased) you can target correct ballistics – these two areas should start to marry up together with crisper striking of the ball.
A good fitter will get your launch, spin and land angle to perform in the correct way to optimise your carry and total distances relative to your your angle of attack and club speed. With a good overview of all of these aspects you will see your longest and straightest drives.