i've done it a few times, but not in a few years...i like the cajun injection, but anything is probably good. i'd google for the best tips, but from what i recall
1. put the bird in and empty bucket. fill with water to cover bird. take bird out. mark water level. dump water out, fill with oil. if you just guess you could overflow with hot oil and that would be bad..
2. make sure your temp is stable before adding bird. temp will fluctuate some because of bird temp...you might have to adjust the heat...or just wait it out...i forget
3. dont leave it unattended
...and make sure to let it rest for a while before cutting into it