Well as you said, the choice is yours haha
Why not try to copy a standard military loadout. You can pick up british DPM, desert or MTP kit fairly cheap, or even US kit. All you really need is the trousers and a smock. I personally have never worn a shirt if i can avoid it, even on operations. Just go for a t-shirt and smock on top (or a UBACS).
As for boots, just pick up a study pair that give support and are light weight (black leather will go with most loadouts and not look out of place)
Head gear is really up to you. Helmets look cool and allow for attachments but if you source a proper one they can be heavy if you're not use to them. Alternatively go for a bush hat, light weight and again will look good with most loadouts.
Webbing really is taste dependant. I have several different sets. As a minimum, in my opinion, you will need ammo pouches and a utility pouch (so may be a leg set up with drop pouches)
good luck