Start with the obvious setup
SOAS explicitly recommends Citymapper and the TFL app, plus either an Oyster card or contactless payments. That is the first transport checklist sorted. Do it before Welcome Week fills up, not in the doorway of a station with five other decisions already in your head.
The brochure also points new students toward campus tours led by Student Ambassadors from the walkway between SOAS buildings, which is a useful way to make the on-campus part of your route feel automatic early on.