First Gun & Questions

Welcome all. Got myself my first handgun last Sunday and picked it up today.

Went with the 43X MOS. My questions were, what should I do now? I definitely want to get a lot of practice in, considering buying 500 rounds of FMJ and going to the range.

I think I plan to carry it only when I go out. My questions are, should I make any modifications or buy any attachments for it?

I was thinking of getting an optic, and maybe a magwell, but I wanted to know from you all what you recommended.

If I get an optic, should I get a cheaper one like the Swampfox Sentinel, or shell out more money and get the Shield RMSC? Or, just get the slide milled and attach a Holosun?

I look forward to what you all recommend. Thank you in advance.