Every sign has a default behaviour and a default depletion. Self-care, astrologically, means refilling what your sign tends to spend.
Fire signs — refill rest
Aries, Leo, Sagittarius burn energy publicly. Real self-care for them is doing nothing, alone, for an afternoon a week.
Earth signs — refill play
Taurus, Virgo, Capricorn over-work. Their self-care is unstructured fun — they will resist it the most.
Air signs — refill body
Gemini, Libra, Aquarius live in their head. Their self-care is anything that uses the body — yoga, walks, dance.
Water signs — refill boundaries
Cancer, Scorpio, Pisces absorb others' moods. Their self-care is solitude, water and a clear no.
Read your full chart in the natal chart.