The only thing you need is to make sure that your cell phone has enough power so that you can actually show the ticket (copies etc. are no longer accepted, as there has been large-scale fraud in the past). Sometimes there is also a conductor who has had a bad breakfast and wants to see your passport along with the ticket (officially the DT is only valid in combination with an ID), so don't bury it in your suitcase.
Also i read if i have a non DT train such as a Ice train in my route, i will only be partially charged, how does that work also?
Please don't board a long-distance train (ICE, IC, EC) with just the DT. This will result in a hefty fine (€60) and a subsequent ticket purchase at the expensive standard fare.
What you can do, however, is to specify that you have a DT when booking in DB Navigator. You will then receive a ticket for the ICE portion only. However, you will then have two different tickets and your connection is not protected. The usual workaround is to book the ticket from the last stop of the regional train before changing trains. Example: You are traveling from Salzburg to Berlin, namely from Salzburg to Munich with the DT, from Munich Hbf to Berlin with a train-specific saver fare. You will book the ticket to Berlin from Munich Ost, the last station before Munich Hbf. If your train from Salzburg arrives late in Munich, you are still entitled to continue your journey on another ICE train.