It does depend a great deal on your training and experience, Ross A has a Houston link for training that seems professional and reasonable, just from looking at the Website, no experience with them. If you are married you would be well off to get your spouse involved too. I guess there are a number of guns depending on what or how you think you will use it. For concealed carry a smaller gun would normally be used, You could use a very small North American Arms 22 Magnum is a five shot single action revolver, but it is difficult to aim well, hard to shoot rapidly and very slow to reload. It is lethal. The next and a lot better choice is a Kel Tec P-32, a seven +one capacity, quick reloads with a spare magazine, softer shooting than 380 rounds and with Underwood 'Cavitator' ammunition it is likely powerful enough. Dependable. Moving up to 380 there are a ton of choices. Small but snappy Kel Tec P-3AT (same size as P-32, but one round less) or similar Ruger LCP, bigger 380 but softer shooting is the Glock 42, 6+1. Three pocket nine millimeters on my list would be the Ruger LC9s (I like the Pro version as it has no external safety) 7+1. Glock 43 is a little bigger, 6+1 and the XDS 9, easy to shoot great sights standard, 7+1. The XDS also comes in 40 S&W and 45 ACP. My 45 XDS is easy enough to shoot, accurate, so is the 9. If you just wanted home defense, then a full handgun of better a long gun like a AR or shotgun.