When you get the turn instruction to enter a highway it is a simple “keep/turn right” (or “keep/turn left” if left hand traffic). E. g. here.
From my point of view there is a fairly easy improvement possible (I hope I’m not too naive here):
If you are coming from another major highway (primary, secondary, tertiery, unclassified, residential, …) and going to the key/tag “highway=motorway_link” the instruction could be something like “enter highway”. The tag “motorway_link” is used 711.000 times all over the world, but of course not all of them are coming from another major highway. taginfo
If in combination with the key “destination|destination:forward” or “destination:ref” it should be used in the instruction as well.
This would be a great improvement for the car/motorcycle instructions from my point of view!