This is a very generic list for all sidemount courses. You will need to contact your specific instructor for fine-tuning, as it can be done differently.
2x Regulators
-- Right Side with 6" HP SPG & 7' Long Hose Regulator (drysuit hose, if used, may come from here)
-- Left Side with 6" HP SPG & 28-32" Short Hose Regulator on bungee necklace, with LPI inflator hose (length varies with rig).
Sidemount BCD system
Lots of options here.. dedicated rigs (Razor, UTD 'Z', Hollis SMS50, Armadillo etc), hybrid rigs (Hollis SMS100, DiveRite) or BP&W adapted (OMS Profile)
Lots of options on bungee systems, butt plates, harness, wings, clips, hoses.... you name it.
Do you have any preferences, goals... 'anything' that can help us tailor advice? Some feedback from your future sidemount instructor would go a long way...