For Abbeys or German Castles we put that tile on hold for next move.
I also recommend trying strategic variant with having 3 tiles on hand and choosing one.
Here's how we rule it, with some adaptations to prevent conflicts and make it work with mega-carcassonne games :At the beginning of your turn:Reveal your tile(s) drawn at the end of last turnIf you have more than one tile (fortune tellers), choose the one you'll playIf the tile contains a dragon icon and no volcano has been placed yet, discard the tile and draw another oneIf the tile contains a wheel of fortune, peasant revolt, hill or dragon icon, perform the corresponding action now (this is so you can't delay such actions by using special tiles)Play the tile or keep it for the next turn (don't discard it) and use one of your special tiles (halflings, German castles, abbey). In that case, you do not draw a tile at the end of your turnIf the stack is empty at the beginning of your turn:You are not allowed to use a special tile (halflings, German castles, abbeys)If you have a tile drawn during a previous turn, you may play a turn with it, otherwise, you skip your turnThe game ends once every players used their tiles drawn from the stackAt the end of your turn:Once you performed every of your turn's actions, including double and triple turn (message, 20 anniversary, builder, saint-Nicholas):Draw a tile and do not show it to other playersDraw one additional tile for each fortune tellers you ownIf you played one of your special tiles (halflings, German castles, abbeys) and so you already have a tile left in hand (or more if playing with fortune tellers), do not draw any tile, you already have one