Probably the best first gun is a 3" or 4" medium framed revolver, assuming you want to learn and have something you can defend yourself with (not everyone has the budget to buy a .22 now and something else later when they are able to handle a gun safely for defensive use). Something the size of the Ruger GP100 or S&W L-frame (586, 686, 520, 620) are great in that they are fairly heavy so shooting .38spl is very low on recoil, and transitioning to .357mag is fairly easy. If you may also carry you may want a K-frame. They are a little smaller and lighter, I think they handle much better, .38spl out of them is pretty easy on the hands, but .357mag can be a bit stout if you aren't ready for it (but I really don't think it is bad at all- .357mag in a K-frame is one of my favorite combinations). You can shoot .38spl out of any .357mag revolver for light recoil and cheaper ammo when starting out (and for regular practice), you can shoot the more expensive and powerful .357mag for fun when you are ready, both many .38+P and .357mag loads make for wonderful home defense or CCW rounds, and you can even hunt with many .357mag loads (or use them for bear defense).
For auto pistols I prefer 9mm for a new shooter who also wants something that can be put into use for defense. It is much cheaper to shoot than many other auto calibers, recoil is relatively light, and it is suitable for HD and CCW.
If you have something else for defense, .22lr is ideal for new shooters (and a must for all shooters). Almost no recoil (makes prolonged practice sessions easy), very inexpensive ammo (makes more practice easy), often quite accurate, and if you get the right one it can be quite fun. As a new shooter you probably won't be ready to use your gun for HD and CCW yet, if you will be able to afford another gun later when you are ready for a HD/CCW capable gun, get the .22lr now.
All that said, the SP101 is a great gun, but it may be a little small for a new handgun shooter. If you are set on this gun instead of a bigger gun, look for one with a 3" barrel (the longer sight radius will make accuracy easier).