What's the best way to defend headers with small players?

Unfortunately I've gone into my current season continuously on the back foot in the air. I seem to constantly concede from these crosses in the box. So I either need to stop the crosses or win the headers... preferably both!

You need tall defenders with good heading, positioning and jumping reach, if you don't have them or can't get them you're in trouble

Well then we're in trouble lol. I guess I'm gonna have to focus on winning the wide positions then.

You can compensate for it in set pieces by having your taller strikers or midfielders in the box.

If you have a short defence though I'd push the line up (Move higher up) or the more extreme push right up option, to force the opposition to try and play through balls. You'll need pace to get it to work though!

Alternatively close down the wings at all times.

Until you get players who can head the ball, focus on stopping the crosses. Close down as much as you can and try to play high up the pitch.

Other thing you could do is make sure you play someone in front of the back 4. Extra chance of winning a header and even if you don't you have an extra body that might pick up the 2nd ball. Same goes I suppose for playing 3 x CB's.

Just to clarify: I thought it would be completely irrelevant if they are small, only jumping counts?

I'm in this situation. My defenders are quite quick so I can play a high D-line to keep oppo strikers too far out to head on goal that way. I also tight-mark wingers and put them on their non-crossing foot (which is not always weaker foot). I'm still a bit vulnerable at corners but overall the tactics are quite effective.