What are you using it for? What do you want/expect from it?
Use will determine what the appropriate upgrades are.
Is it going to be used for HD? SHTF? Patrol/duty? Range gun/plinker?
Make sure you gain proficiency with the irons before you start spending massive amounts of money on optics.
Learn the weapon system front and back, and it will make it easier for you to determine what upgrades are necessary, and which are not.
For 95% of people, a stock, factory AR will be sufficient, and need no active upgrades. Some upgrades improve function, some specialize the weapon, some will improve reliability, some improve comfort or utility, some offer tactical benefits, some offer competition benefits, some don't offer benefits at all.
Some look cool, some look like shit, some you'll never even notice, most of the ones on the market are a waste of money, but some are great investments.
HTH,
~Augee