Well maybe it'd be nice to give them some secrets too such as Gold Dust(gaara's father's jutsu) and Iron Sand(third Kazekage's Jutsu)
Moving past that their sand coffin is a auto kind of thing making the user not have to really catch you just be close enough.
-If the sand coffin as a projectile that if hit someone would capture them in a sand coffin that would be nice.
Sand Tsunami should cover anyone hit in sand for awhile causing them to be slowed down and if a sand user uses sand burial on them it should do a fraction of sand coffin's damage but free them from the sand's slow down effect
Sand Shuriken as a single tile attack
Sand bullets as a 3 tile attack that does lower damage than sand shuriken but causes the opponent to get sand on them slowing them down for some time(sand burial option possible with much lower damage)
Sand shower as a 3 by 3 AOE that causes a slow down to anyone hit giving the option to sand burial them for much less damage
Back to the Iron and gold sand/dust, Maybe a different way to attain gold dust and a different way to attain iron sand
Iron sand could do most of the things regular sand could do besides sand sphere and flying due to it being as heavy as it is
iron sand would also be a bit stronger than normal sand expecially it's sharp projectiles
Gold sand/dust would have about the same jutsus as regular sand but it'd be weaker due to it being lighter then normal sand