How do I use elephants properly?

[Viking]

...2) retreating from missile fire, especially fire arrows; and 3) using them in tandem with another unit right at the elephants' feet (skirmishers or cheap melee infantry are great for keeping enemy skirmishers out of range).
...
R:TR takes a more realistic (though less enjoyable) approach: the elephants are much easier to kill, especially with javelins, and they rout if you breathe on them wrong.

Also in vanilla those javelins are very deadly for elephants, so for gods sake keep `em away from those!

[Tigranes]

Maybe that's why I'm not good with them. I use R:TR.

I'll test out the suggestions, thanks!

[Nelson]

I use elephants when I need to screen my flanks because I’m outnumbered. Sometimes I try to cave in an enemy flank with them. I never have them near the center. In fact, it’s not uncommon for me to leave them out of the fight altogether. They are also good for smashing in the gates of palisades and wooden walls.

[itsgottabeworthatry]

I use them to throw the enemy lines into disarray or when I need to get out of a stalemate. Personally I think they are most effective as psychological weapons. I mean, they don't kill as much as one would think, I simply let them run around, sowing terror in the enemy ranks, they are most effective this way, just make sure they never stop. Keep those elephants moving.