If an ass goes traveling it will not come home a horse.
If ifs and ans were pots and pans, there'd be no trade for tinkers.
If the mountain will not come to Mahomet, Mahomet must go to the mountain.
If the young knew and the old could, there is nothing that couldn't be done.
If we did not flatter ourselves the flattery from others would not harm us.
If you can't be good, be careful.
If you can't get people to listen to you any other way, tell them it's confidential.
If you don't stand for something, you will fall for something.
If you have to swallow a frog, try not to think about it. If you have to swallow two frogs, don't swallow the smaller one first.
If you play with fire you get burned.
If you trust before you try, you may repent before you die.
If you want a thing well done, do it yourself.
If you want to be revenged, hold your tongue.
If you want to know what a man is really like, notice how he acts when he loses money.
If you want your eggs hatched, sit on them yourself.
If you wish for peace be ready for war.
Imagination gallops; judgment merely walks.
In calm water every ship has a good captain.
In for a penny, in for a pound.
In teaching others we teach ourselves.
Indecision is the key to flexibility.