8 Ohm sub to 4 Ohm Amp?
 

Can I, how can I, or what is the best way to wire one single voice
coil, 8 Ohm subwoofer to a 2-channel, 4 Ohm Amplifier?

8 Ohm sub to 4 Ohm Amp?
 

to get the best from your amp you need to bridge it. This means run in
mono. Most car amps can run 4 or 8 ohms in mono, to get the best output
from your amp you could use another 8 ohm sub and wire both together to
give you 4 ohms. How?? wire the + to the + on both subs and - to - then
take + and - from either one sub to the mono connection on the amp. Hey
presto! You have bass!!!