Structure:

If+Present simple/will+Infinite

 

WILL

In the second part of the sentence you can use "going to" or the "Imperative" as well as "Will".

Ex: turn off the TV when you go to bed

Ex: Change the channel if you want

 

IF

"If" can be substiutted by the following words:

"Unless + positive verb" can be used instead of "If……not" You'll be late unless you go now = You'll be late if you don't go now

When Turn off the TV when you go to bed

As soon as is more immediate than when. I will go to the toilet as soon as the commercials start.

In case: use for something you do as a precaution. Ex: Take your umbrella in case it rains.

Until (or till): up to the time when. Ex: we'll stay here until the dinner is ready

Use the first condional for Likely or possible situations.