Good lightweight boots with ankle support. Comms are a huge part of effective airsoft. Not being able to communicate with your team is a massive disadvantage. Grab a reliable headset as well and not just a radio. Radios can give away your position and that of your teammates easily if they are just on.
Hop-up, barrel, nozzle, seal as Thunder said. That'll get up your efficiency and consistency. Also invest in high quality BBs, such as Bastards, and run the highest weight your gun is comfortable with. If you need more jam you can up your spring power afterwards which'll unlock the ability to effectively run much heavier ammo, but then you may need to upgrade everything else to handle the harder cycle pressure. Things like reinforced gears, a stronger motor and then of course higher voltage batteries to handle it all. Things like mosfets are more about responsiveness and rate of fire, not really a must for upgrading, but more a fine tuning part.
Grab an optic that's effective for your playing style, skill as well environmental limitations. Also grab good quality and effectively disruptive camouflage. Get what works over what looks cool. I usually recommend a transitional pattern to start for versatility. Then you don't need to buy several pairs right away.
If you get an accurate 80-ish feet out of your pistol, well then you don't need to upgrade it right away, it's doing its job. So, not really a priority. Buy high quality, ballistic eyewear. Probably best to have at least two pairs just in case.
ďREALITY IS LIKE A STONE. TO MANY ITíS HARD AND COLD, THEY CANíT HUG IT OR EAT IT, IT ONLY FRUSTERATES THEM AND DOESNíT DO THEM MUCH GOOD. TO OTHERS ITíS STRONG AND DEPENDABLE, YOU CAN BUILD WITH IT, BUILD UPON IT, OR WORK WITH IT, ALSO USE IT TO SMASH PEOPLE IN THE FACE.Ē