If you ship your bike home from the end point of your tour, you will probably have removed you seat post and saddle in order to fit the bike into whatever case you used. When you get home and are putting the bike back together you will want to end up with the saddle at the same height relative to the pedals as it was when you took it off. A simple way to ensure that is, before you remove it, to wrap a piece of tape (electrical tape works best) around the seat post where it enters the frame. Then, when you put it back, just insert the post to the same spot.
An aluminum seat post inserted into a steel frame will result in galvanic corrosion between the two metals. If not removed and cleaned and re-lubed periodically the seat post will become well and truly stuck and may need to be cut out. Removing it for a period of time will also allow any moisture which might be in the frame tubes to evaporate. Applying grease to the inside of the seat tube rather than to the seat post results in less of the goop squished out onto exposed bits and ending up on your clothes.
Don’t use grease on a carbon post or with a carbon frame. Use a special paste made for this purpose. The paste won’t damage the carbon and it has a little bit of grit to it that will help hold the post in place without over tightening.