Congratulations on deciding to learn a weapons system and become more proficient in firearms skills. The main question I have, is what is your purpose? recreational target shooting? IPSC? personal defense or home defense? Each of those will require a different mindset and weapons system.
If that is you, in your avatar, then I am going to assume you are a large man with average to larger hands. Handguns are like boots, one must fit perfectly or you will never learn to shoot with speed and accuracy. My first suggestion would be to go to an indoor gun range that offers rental pistols and shoot a variety of brands.
I and others on this forum, have written a lot of material on weapons defense strategy and training. I would encourage you to read the last two pages of the "knife thread" where I gave my opinion on weapon selection and read through the "Active Shooter thread" for information on surviving an active shooter scenario. Lot of very solid information here and forum members will help in way we can. Good luck.