Buy anything in the low $1 range or below. Expect resistance around $1.50. We're in the middle of range currently so we could go either way.
Keep an eye on correlations as well.
Over the last year Cardano has had a .67 correlation with ETH and a .42 with BTC (A 1.0 correlation means they move perfectly synchronously. A 0.0 correlation means they always move opposite). Though the entire crypto space is correlated to some degree, keeping an eye out for products with low correlation to each other may be valuable.