Try to buy a good quality sliding system, these typically have very good and easy adjustment for the sliders to align the doors. I personally prefer systems with wheels both top and bottom as I feel it gives a better feel to the doors. I also buy systems that are greatly over rated for the weight of the doors that I'm fitting. The abuse factor is what leads me to higher rated systems. People....children ......teenagers tend to pull, slam and swing off the doors! If the adjustment system isn't rock solid you either have doors that are quickly out of alignment or more worrying potentially can come off the rail systems.
Secure the rails expecting the abuse. Lots of good long quality fasteners.
If a bottom rail is used. Think about the room flooring, carpets often need the bottom rail raising to allow 1" fir the carpet and underlay to be laid neatly against it. Equally the floor is seldom flat or plumb and often needs a Hatton to level it up.
The best approach is to get the rails plumb and (must be) parallel with each other in order for the doors to move correctly. Often the rails are left out of plumb but parallel, with the top rail adjusted to make the two rails parallel.
Depending on the storage division arrangement plan the door overlap to hide any vertical dividers. Make sure the overlap is big enough!
Walls and ceiling are very very rarely in plumb, so plan to allow trim that can be scribed. Think ahead on how your going to attach the trim panels. E.g. Screwing them in from the inside will on one side show (door that's overlapped) unless the trim overlaps the doors, which depending on your design is not always feasible.
I'd take a look at how they are built in show rooms, decide what you like and adapt for your own design.
