You must first evaluate the situation/s you find yourself in most often. Examples: number of people, hostile environment, low or no light...to name a few. Then decide the caliber that would suit your needs. Think stopping power, capacity and availability of ammo. Next find a gun in your chosen caliber that fits your hand and feels like it's a part of you. Then buy a holster that you feel carrying, a ton of ammo and other accessories you may need. Lastly practice till you are the bomb. For what it's worth try the Glock 26/27/30. Have fun shooting. Also don't forget training.
Oh how I love reading these types of threads. Always interesting to see the differences in tastes. Since the OP specifically mentioned starting a collection of handguns I will cast my vote for those models that are tried and true. Also, guns that IMO characterize a specific type/action of handgun.
1) 1911 or Browning HiPower
2) Glock 19/23
3) Sig Sauer P220, P226, P229, P239
4) K Frame Smith & Wesson Revolver Model 10,15,19,etc.
5) Smith & Wesson 442/642
I'd avoid a CZ 75 for the first of the 5. If you get a CZ 75 first, the other 4 will just be CZ 75 variants. If all of my guns were stolen and the insurance check covered any 5 new ones, I'd go with:
Kimber Stainless Compact in .45 for daily carry some of the time
Springfield full size 1911 for range fun
Sig P238 for pocket carry all of the time
CZ 75 Compact for daily carry most of the time
Firestorm 22 for cheap plinking
Radom 9x18mm because it is cool, Kahr Arms CW9 because it is sooo easy to carry, S&W M&P .45 because it is a beast, Phoenix Arms HP22 22lr because I like it, and a Ruger Blackhawk .357 Magnum because it makes me feel like a cowboy. Really thats just the five handguns I own and I just learned how to include photos in my posts.
Glock 23 - For a dirty, ugly, work gun.
LC9 - For awesome firepower, and great concealment
Kimber 1911 - For, well if I need to say, then no one knows true quality handguns.
Magnum Research Micro Eagle - Ultra deep concealment
Smith & Wesson Wheel - For jam-free BUG.