installing new switch & 2 receptacles
Grounds get tied together, to the switch and to the box if it's metal. Use pigtails where needed. Neutrals (whites) get tied together separately. Incoming 'hot' gets connected to one terminal of the switch and any (outgoing) load wires (usually black) that you want 'hot' all the time, use a pigtail to the switch. The load wire(s) you want switched will get hooked to the other terminal of the switch, use a pigtail if necessary.
Please give a better description of the circuit if you require more assistance.
Just because you can, doesn't always mean you should