Practicing movement and timing will go a long way! For BLJs a lot of people just mash as fast as they can when in reality, your rhythm is important too! Having a good camera angle can also help, I like to use C down mario cam which helps keep the camera straight on the stairs. Watching other runners (beginner and advanced) helps you learn a lot of things too! Go check out smaller people on twitch and if you see them do something you have had issues on, ask! Most people are willing to offer tips.