well, the coils (4) send current to your plugs...so if your coils are bad then your new plugs won't work.
Check this out:
http://foxed.ca/rx7manual/manuals/RX-8FSM/
^^danno is also on to something....it could be as simple as a flooded engine. CHeck the coils as per the FSM (Factory Service Manual) and get back to us....Unflood the motor and try again.
IF both come back OK then look into the starter.
Again, it has to be one of the following:
Air, fuel, spark...