Maybe deadlift is not the best exercise but it is a must do exercise especialy when you are building your strength base. Depending on your workout routine it can be difficult to do deadlifts more than two times a week. This is because it hits your nervous system hard and you need time to recover. This is why you need other exercises to get stronger in doing deadlifts. To do this first you have to ask yourself which are the muscles that are most needed to perform a deadlift. Then you have to chose the best exercise for them.
Strong legs are most important to get stronger in deadlift. Dead-start squats are the best and do the most carryover to a deadlift. You should set up the bar to match your hip position for deadlift for maximum progress. It will improve your explosiveness and strength in squats too. For faster progress do sets of 3 to 5 reps.
Second most important thing is to improve your core strength. Weighted plank is a great exercise for this. Best to perform this exercise from 40 seconds to 60 seconds. When you can hold for more than 60 seconds, just put more weight. Do not arch your back when you do a weighted plank. You should not have much tension to your shoulders or lower back because it can be dangerous. Tighten your abs while performing the exercise for max results. The weights should be between your lower back and glutes.
Lats do not take as big role in deadlift as legs and core, but are important too. They decrease the required hip and spinal extension in conventional deadlift. Standing Lat Pushdown on Cable Machine is the best exercise for that purpose. Do from 8 to 12 reps per set and hold for 2-3 seconds each rep.