Don't sweat it. If the range you go to is anything like the one I frequent - about half or more of the people there will be fairly inexperienced shooters. You can spot them right off. New looking gun (almost always a large caliber auto), Still have the original case for it (in pristine condition), ammo brought out in the paper sack they bought from the store in not more than a couple of hours before. No rags, tools, oil or other stuff. Disposable ear plugs. Most don't have shooting glasses or hats to keep junk from flying into their eyes or down their collars.
More often than not a couple of middle aged "baby boomer" types or kids that are just barely over the legal age to buy a gun. Very often a guy and a gal. The gal is humoring the guy by touching off a few rounds from some gigantiac blaster that he no doubt has acquired to satisfy some testestrone driven urge to posess at least the equivilent sized "member" of his perseived peers. None of the above manage to put more than 20 rounds into a 12 circle at 7 yards. The ritual is usually completed in about 20 minutes (the typical time required to set off 50 rounds from a $20 box of ammo).
The more seasoned folks though will be off away from the crowd. They obviously pace themselves - their targets prove it. The "wrappers" have obviously long worn out. No paper sacks - just well worn range bags & ammo cans. No "cammo" clothing, combat boots, SWAT Holster Rigs, mirrored sunglasses or tee shirts with sayings like "Kill E'm All & Let God Sort E'm Out". Their firearms look well kept - but certainly well used. Comfortable but clean clothing that they are not afraid to get soiled. Appropriate eye & hearing protection.
And, if you wait until the the seasoned folks have finished shooting and properly secured their firearms, most will freely share with you what they have learned and answer questions you may have. NEVER reach for one of their firearms without permission - most will gladly let you handle them if you ASK though. Above all, have fun. Be safe, pay attention & be aware what's going on around you, be respectful of others - but don't worry about "appearance". The "newby's won't know the difference - and the seasoned shooters won't care. With time, you will learn what to bring & what to wear.