I’ve improved my swing by a 5 step routine I do each time before I take a drive, firstly I make sure my feet are aligned with the direction I am hitting in, next I make sure my left foot (for right handed people) is aligned with my ball, next I make sure my drivers face is positioned in the right way, next once I’m ready to hit my drive I imagine a rail road track or Parallel lines in alignment with my feet in the direction I’m hitting to give me an idea where I’m aiming, and the final step I make sure to keep my head down and then I do my back swing and swing through the ball which is key, it sounds like a complicated routine which takes time but it really isn’t, I do this process almost naturally now, also what I find useful to help my drive go straight is imagine an elastic band pulling my arms together as I take my swing.