IF he comes, I will help him. (you don't know if he comes)

IF she arrives early, I will still see her. (You don't know at what time she arrives)

 

IF he had money, he would pay for you. (you don't know if he has money)

IF she went to the party, I would go too. (you don't know if she is going)

 

IN THE PART OF THE SENTENCE WITH IF, YOU CAN NEVER EVER PUT WILL OR WOULD, BUT ONLY THE PRESENT OR PAST SIMPLE.

​

IN THE OTHER PART OF THE SENTENCE YOU PUT WILL OR WOULD WITH INFINITIVE.

 

IF+ present simple ---------- will + infinitive

IF + past simple   ------------- would + infinitive