Good afternoon, I recently purchased a Bushmaster M4 MOE rifle. This is my first AR buy. While I eventually want to build my own rifle, the bushmaster had the platform and look I wanted. My question is around upgrades. I will mainly be using this for fun. I have a Glock 23 that I carry and use for home protection. I will also be added a berretta a300 shotgun day after Xmas. My focus for my AR is performance and improving accuracy. What are some things I should look at first? Any and all opinions welcomed. Thanks for teaching a noob!