Take off your crank arms, take the bottom bracket tool and take out the bottom bracket. Clean out the threads and apply grease. Install the bottom bracket as tightly as possible. Tighten your crank arms so their tight enough to be stationary but without stripping the bolt and/or over tightening them; grease every thread. Clean your chain and tighten the chainring bolts and grease the bolts and lubricate the chain. Make sure your cog and lockring are cleaned and greased and tight. Tension your chain properly as well.

Is your chainring and cog both the same pitch? Is your chain 1/8 inch and the chanring and cog 3/32?

There really isn't that much that can go wrong. I find that if I spend the money on really nice parts and figure out how every tiny thing involved works together properly, I don't have that problem.

I did however do some pretty sketchy things when I first started repairing and servicing bicycles out of ignorance, so I can relate to the random noise and not knowing where it's coming from.