Tek-9's are known jam-o-matics. Anyone using a machine gun for home defense has watched a few too many movies.
The Desert Eagle is not a pistol for beginners. The recoil, weight, and sheer dimensions of the gun will cause a lot of bad habits.
Start off with a .22 rifle, then move to a .22 handgun. The minimal recoil will make it quite easy to learn the basics.
Any large manufacturer makes a solid firearm. Glock, Beretta, Sig, HK, S&W, Springfield. All depends on what the tool will be used for and most imporantly, the person shooting it.
Try taking an NRA course available at most shooting ranges. Gives you a solid foundation from which to build on and they're pretty inexpensive for the wealth of knowledge you attain in various aspects of cleaning/owning/using firearms.