Although most new games will try to have a few references to the previous game, it is not often that the choices and things you did in the last game would affect the new game.
In the case of Shadow of War, that is exactly what players should expect. According to Monolith Productions, you save file from Shadow of Mordor will be carried forward to the new game and what you choose to do will affect the experience of the new Shadow of War.
This means that some of your enemies from Mordor will appear in Shadow of War. Of course, you will also be getting back some of your best allies. Of course, that is only if you have played the first game.
If you did not and would like to start playing now while you for the new Shadow of War to arrive, the game is now free on the Xbox and PC so there is no better time to do it.