The Buddha tells the Kalamas to choose a teacher wisely in the Kalama Sutta based on the usefulness or skillfulness of the teachings, as well as you can identify the characteristics of the "disciple of the noble ones":
"So, as I said, Kalamas: 'Don't go by reports, by legends, by
traditions, by scripture, by logical conjecture, by inference, by
analogies, by agreement through pondering views, by probability, or by
the thought, "This contemplative is our teacher." When you know for
yourselves that, "These qualities are skillful; these qualities are
blameless; these qualities are praised by the wise; these qualities,
when adopted & carried out, lead to welfare & to happiness" — then you
should enter & remain in them.' Thus was it said. And in reference to
this was it said.
"Now, Kalamas, one who is a disciple of the noble ones — thus devoid
of greed, devoid of ill will, undeluded, alert, & resolute — keeps
pervading the first direction [the east] — as well as the second
direction, the third, & the fourth — with an awareness imbued with
good will. Thus he keeps pervading above, below, & all around,
everywhere & in every respect the all-encompassing cosmos with an
awareness imbued with good will: abundant, expansive, immeasurable,
free from hostility, free from ill will.
At the same time, in the Mahaparinibbana Sutta, the Buddha advises the sangha to take full refuge unto the dhamma and depend on themselves.
"When he dwells contemplating the body in the body, earnestly, clearly comprehending, and mindfully, after having overcome desire and
sorrow in regard to the world; when he dwells contemplating feelings
in feelings, the mind in the mind, and mental objects in mental
objects, earnestly, clearly comprehending, and mindfully, after having
overcome desire and sorrow in regard to the world, then, truly, he is
an island unto himself, a refuge unto himself, seeking no external
refuge; having the Dhamma as his island, the Dhamma as his refuge,
seeking no other refuge.
"Those bhikkhus of mine, Ananda, who now or after I am gone, abide as an island unto themselves, as a refuge unto themselves, seeking no
other refuge; having the Dhamma as their island and refuge, seeking no
other refuge: it is they who will become the highest, if they
have the desire to learn."
Please note the last advice on the "desire to learn".
- Take the Dhamma as your island and refuge
- Depend on yourself
- Have the desire to learn
- Learn from teachers whose teachings you find to be useful and skillful (need not be arahants)
- Identify that the teacher is, preferably, a "disciple of the noble ones" (see above)
- But don't depend on those teachers - depend on yourself and the Dhamma
- Alagaddupama Sutta also warns of making sure that we understand the Dhamma properly and also not getting overly attached to it ("In the same way, monks, I have taught the Dhamma compared to a raft, for the purpose of crossing over, not for the purpose of holding onto.")