When you are writing conditional sentences the golden rule to remember is this:

Never use “will” or “would” in the if-clause.

When I pointed this out in a recent training session everybody said that they already knew the rule. But I reckon I still have to correct this mistake about two or three times every day.

Here’s an example of what I mean (this is a 2nd conditional):

WRONG
If the TPO would take over such a role from the manufacturer or seller, it would simply offer a network of service providers equipped with repair and replacement capacities.
RIGHT
If the TPO took over such a role from the manufacturer or seller, it would simply offer a network of service providers equipped with repair and replacement capacities.

As you see, in the part of the sentence that follows “if” (the if-clause), “would” is incorrect. However, “would” is correct in the main clause.

Here’s another example (a zero conditional):

WRONG
In the event that production costs, market circumstances or government interference will necessitate a review of the prices, both parties agree to reconsider them in good faith.
RIGHT
In the event that production costs, market circumstances or government interference necessitate a review of the prices, both parties agree to reconsider them in good faith.

Notice that in this example the word “if” is not used. Instead, the if-clause starts “In the event that…”

It is important to remember that the if-clause can start with all sorts of different words and phrases, e.g.: In the case that… In the event that… When… Where… Provided that… Unless… etc.
Also remember that the if-clause doesn’t have to be the first half of the sentence.

This example is a 3rd conditional:

WRONG
The affected party would not have entered into the contract if it would have known the true state of affairs.
RIGHT
The affected party would not have entered into the contract if it had known the true state of affairs.

As usual, there are some exceptions when you can use “will” or “would” in the if-clause (most notably in polite conditionals). But 99% of the time you will be correct if you apply this rule.