Translation:One must consider the facts before the decision.
antaŭ fari (la) decidon is fine, but I would also accept the Esperanto sentence as it is now. La decido can have two meanings: the act of making a decision, and also the result of this process. So that works well in Esperanto. I understood the English phrase in the same way (decision as a process, not as the result), but I'm not a native speaker...
The noun, "decision" means the result, not the process. The verb, "to decide" or "to make a decision" is the process. If you want a noun for the process, you would say, "decision-making". So one way to translate the above sentence without adding an extra verb would be, "One must consider the facts before the decision-making".