Watson,
Since you posted here in the autoloaders forum I'll assume you want an auto and not a revolver as your first handgun. You said you'll be getting lessons at the local range, that's a great idea. What you now need to decide is what is the primary purpose of gun; self defense, target shooting, or just learning to shoot handguns better? If you strictly want a gun to learn on something like a Browning Buckmark, Ruger Mk III, Ruger 22/45, and several others in 22LR are a good start. Go to your gunshop or range and handle a few, shoot them if possible, and see what fits your hand. If you want something for self defense think back to shooting the Beretta and the Kimber; the 9mm has a lighter but snappier recoil, and the 45 has a slower but heavier recoil, which one was easier for you to control? That will help you on choosing the caliber. After that handle everything you can in the gunshop and see what fits your hand. Then go to the range and rent your top 3 to 5 choices to see what you shoot best. As has already been mentioned many service size pistols have 22LR conversions available so keep that option in mind.
What was my first handgun? A S&W Sigma in 9mm. I bought it because I thought it was cool and it was cheaper than the ultra cool Glock. The Sigma had great ergonomics and a horrible trigger. I next traded up to a Glock 22 in 40 S&W. The Glock is a fine firearm, the trigger is far better than the Sigma, but takes some getting used to. I kept the Glock for several years and then recently discovered the Browning Hi-Power. I fell in love and wanted a Hi-Power bad enough to trade the Glock toward it. It's a great pistol. I wish I had kept my Glock and will probably get another one in 9mm, but I don't regret trading it to get the Hi-Power. My last purchase was a Springfield Armory 1911 in 45 ACP. I bought the 1911 because I wanted a 1911 just to have a 1911, but it is quickly growing on me. Outside of my semi-autos I've become a S&W revolver addict as well. Stick to the major brands, and save yourself some cash by buying nice used guns. Keep asking questions if you need more advice or clarification.