Rehearse the step first
Find clear space behind you before beginning. A reverse lunge is awkward to learn beside a loose bag or a bench you must remember to avoid. Start without dumbbells, stand comfortably and take a modest step back onto the ball of one foot. Pause there briefly, then bring the foot forwards again. This first trial is about placing the foot, not descending deeply.
Keep some side-to-side distance between the feet. Stepping directly behind the standing foot creates a narrow base that may feel more like a balance drill. If the return becomes a sideways hop, try a slightly wider backward placement before changing anything else. Look ahead rather than repeatedly turning to find your landing place.
Add a controlled lowering
Once the step is predictable, allow both knees to bend into a comfortable split stance. Keep the front foot settled and lower only as far as you can return without a sudden shove or wobble. The back knee does not have to touch the floor. A hard tap onto the floor is not a useful target for a beginner learning the movement.
Return to standing deliberately. If the foot arrives with a stamp or the torso swings dramatically, the step length, depth or pace may be more than you can currently organise. Simplify one of those elements. A shallow, repeatable movement gives you clearer feedback than alternating between a deep lunge and a recovery step.
You can practise several repetitions with the same leg stepping back before changing sides, if that fits the exercise you are learning. Alternating every repetition adds another decision and can obscure which side needed a placement adjustment. Neither arrangement should be chosen merely to keep pace with somebody else's demonstration.
Do not turn the backward step into a blind reach
A large step looks impressive on video, but the distance should serve the movement. If you stretch the back leg so far that the front foot feels unstable or the return requires a launch, shorten it. A stationary split squat may be a simpler place to practise if the stepping transition continues to dominate.
Use a fixed support when appropriate, keeping the hand contact light enough that you can tell what your legs are doing. It should not be an object that moves when you pull on it. A trainer can help you choose between supported practice, a stationary version and a different exercise if the lunge remains uncomfortable.
When you add weights, check the area again and keep them clear of your legs. Finish the final repetition before walking towards the rack. The slower setup is not wasted time: it means the exercise starts with a known foot placement and ends with a deliberate return, instead of becoming a series of hurried steps backwards.