The basic protocol is

• collect blood using anticoagulant (around 100uL)
• add Fc block (0.1ug/10uL blood)
• incubate 10 min
• using stain buffer prepare antibodies dilution and controls (using separate tubes)
• add blood (at least 5uL but I recommend more due to loss)
• incubate 30min RT (in the dark)
• add 10 volumes of lysis solution (I recommend BD Pharm Lyse)
• incubate at 37oC for 3min or RT for 15min (also in the dark)
• centrifuge 200 X g for 5 minutes
• carefully aspirate supernatent, without disturbing pellet.
• add 1X PBS containing 1% FBS 
• centrifuge at 200 X g for 5 minutes
• carefully aspirate supernatent, without disturbing pellet.
• resuspend pellet in 2% formaldehyde
• analyze

Just be sure to have all the correct antibodies, and controls