Need to knows?
You need leather (perf'd in your case, since you're in a hot climate).
You need it to fit.
You need to wear it all the fucking time with very few exceptions.
You need armor, CE rated or better (CE level II can absorb more impact). (all decent gear will come with CE armor already...)
You need a helmet that fits and passes all the common standards (this is the place NOT to cheap out).
You need to find good deals on high quality gear if you're tight on money, not normal deals on cheap shit.
edit:
Here's my getup... it does street and track duty until I can afford a custom one-piece:
HJC AC-12 Carbon Vader Helmet
AGVsport Torino Jacket
Dainese Airspace 2 back protector
Teknic Chicane Pants (full circumference zip to jacket)
Added hip armor in pants (saved me a bruised hip at the track methinks)
Teknic speedstar knee pucks
Sidi Vertigo Air boots
Held Phantom gloves
I've been in pretty nasty humidity and heat... it's not fun if you get stuck in traffic... but if you're moving, it's fine. Just stay hydrated.
Also, when riding in the city for short distances, low speeds (<20mph), and hot weather, I'll wear:
Same helmet
Joe Rocket alter ego 2.0 textile/mesh convertible jacket
A* smx-plus short gloves
Hiking boots
Jeans
That's a chance I understand and am willing to accept. If I have a problem in the city, it would probably be a car hitting me, in which case my gear wouldn't do much to save me from the impact. No fucking way in hell am I leaving the city in that gear though.