[willc]

I'll put in my two cents on how the military does things since you are only as good as you sound on the radio and comm brevity is the goal.

VFR - "Mobile Approach, Buck 321 VFR 20 miles north of Mobile request"
"Buck 321, Radar contact 20 miles north of Mobile say request"
"Buck 321 request......"

IFR - "Mobile Approach, Buck 321, 16 thousand, information Golf, Request"
"Buck 321 go ahead with request"

If approach is not busy then just use judgement and add in "request ILS full stop" In our case they know who we are by our callsign and usually what we want so we can get away with throwing everything in on one call.