If you are not sure where to start: try a new sensation before a new dynamic. A grinder, a pinwheel or a flogger is easy to stop the moment it is not working. Chastity and restraints need more conversation first.
If you want to bring it up with a partner: start with a game or a couples toy. A dice roll or a dare makes the ask for you, and a couples vibe adds something new without changing what you already do.
If you want hands free: go for a grinder, a mount or a machine. A toy mount holds a wand or a dildo in place, and a grinder or a ride-on machine lets you set the rhythm with your hips.
If you are curious about electro play: start with a kit. Keep it away from the head and anything flammable, and skip it entirely with a pacemaker or other implanted device.
If you are curious about chastity: start with short sessions. Check the fit and the skin often, take it off at any numbness or color change, and do not sleep in it until you know how it fits.
If you want to go bigger: size up in steps. Warm up with something smaller, use more lube than you think you need, and go slow.
On pinwheels and metal floggers: fleshy areas and a light hand. Keep them off the face, joints and spine, and clean them between partners.