so I've read around forums that the max current from a RPi 3.3v GPIO pin is 50 mA, but since it is the max I don't know if I should take a resistor for 50 mA or for a lower current.
You have been misinformed.
The 50 mA is for the GPIO as a whole. (This applies to the original Pi A & B; the B+ and later (with 40 pin header), including the Pi Zero, have no such limit.)
It is generally suggested that you don't try to draw more than 16 mA from a single GPIO (although the 16 mA figure is actually how much can be drawn before the GPIO can't reliably signal a logical high).
You need to expand your question to explain what you want to do if you want a useful answer.