BEECHCRAFT PLT FLIES WRONG ALT FOR DIRECTION OF FLT.

Narrative

PAX ARRIVED 3 HRS EARLY AT BTR; LA. I HAD NOT FILED AN IFR FLT PLAN. I DECIDED TO DEPART FOR SHV ON A VFR FLT PLAN WITH FLT FOLLOWING. THE GND CTLR AT BTR ASKED FOR CONFIRMATION OF REQUESTED ALT OF 17500 FT; WHICH I DID. THE WX WAS ABSOLUTELY CAVU. APPROX 75 DME S OF EMG VOR; ZHU WANTED TO KNOW IF I WOULD BE STARTING MY DSCNT SOON; AS I WAS AT THE WRONG ALT FOR MY DIRECTION OF FLT. THIS IS WHERE I FIRST REALIZED MY ERROR. I IMMEDIATELY DSNDED TO 16500 FT AND WAS HANDED OVER TO ZFW. I REALLY THINK THAT MOST OF THE PROB WAS THAT I ALWAYS FILE IFR; REGARDLESS OF THE WX. I GOT INTO A HURRY AND JUST DID NOT STOP AND THINK ABOUT THE CORRECT ALTS FOR A FLT NWBOUND. ADDITIONALLY; THE GND CTLR AND ZHU CTLR COULD HAVE ALERTED ME EARLIER. OF COURSE; I KNOW THE FAA IS TRYING TO PLACE ALL RESPONSIBILITY ON THE PIC; AND ACCEPT NONE ON THEIR PART. I THINK THAT WE ALL WILL MAKE MISTAKES FROM TIME TO TIME; BUT IF WE ALL WORKED TOGETHER; THINGS OF THIS NATURE; WHICH ARE EASILY CORRECTABLE; WOULD NOT HAVE TO HAPPEN. APPARENTLY THERE WAS NO OTHER TFC CLOSE TO MY POS AS I WAS NOT NOTIFIED. FROM NOW ON; I WILL NEVER ASSUME THAT THE FAA OR ATC WILL CORRECT OR MAKE SUGGESTIONS TO A PLT TO MAKE OUR SYS BETTER OR SAFER.