There are lots of different things you can do to help your child develop the independence they will need at school. Every child is different and you know your child's needs but some ideas that might help your child grow in their independence are:
Teach your child to put their shoes and socks on independently
Use shoes with Velcro until they can manage laces on their own
Check that your son knows what a urinal is and how to use it so they can go to the toilet on their own
Talk to your daughter if they are not used to going to the toilet with a dress or long skirt on so they know how to do this
Get them to carry their own bag places and to unpack and pack it themselves
Teach your child to take their jumpers on and off by themselves so they can do this at school