Circuit diagrams are amongst the most abstract representations used in elementary physics teaching. How best to support reasoning with them, and indeed, what kinds of reasoning do you want to support? Or, more succinctly, how do you prepare to answer the question
Why are we doing this, Miss? Diagrams play a significant supporting role in reasoning about circuit loops, so starting with thinking about choices made, even after deciding to use conventional symbols, may be productive.
Is there a good convention for orientating the drawing of a circuit (leave aside for the moment the process of introducing representations)? After all, even for a simple circuit, there are many possibilities.
Studying circuits is valuable because it gives insight into switching power. People use circuits for switching power at all scales: remote (electrical) working is pervasive in the everyday lived-in world. You may have other reasons, which will lead you to different conclusions.
If switching power and reasoning about power is central, then drawing the dissipative elements (those where power is switched) vertically enables the representations of power to be arranged so that you can easily compare values.