I would look at Mark Rippetoe on YouTube again (he has many videos all saying the same thing).
Basically, if you set up your body for the lift correctly, there is nothing to focus on besides driving your legs into the floor. The bar will travel along your shins and along your thighs up to the hip as a result of proper set up and extension of your hips when you drive your legs into the ground (not because you are purposefully guiding it along your body).
I think some newbies get hurt bc they think DL is a squat starting from the floor rather than off the rack. Experienced lifters get hurt making heavy-reach lifts where form falters (and they have their body on a compromising position under extreme load). However, they are an excellent full body compound/functional lift that is very important for developing total strength.
Honestly, if these tips and videos don’t immediately help, go get a new trainer next time you hurt yourself. Back pain can be life long and debilitating