This tip deals with the word-initial sequence <hypo->.
First, three oddities:
hypocrisy = hɪˈpɒkrəsi, hypocrite = ˈhɪpəkrɪt and hypocritical = ˌhɪpəˈkrɪtɪkl
In some words the second syllable of the sequence bears the main stress of the word and the pronunciation is haɪˈpɒ. Here are some examples:
hypocorism hypostasis hypotenuse hypothesis hypothesise hypoxia
There are a few words where it is the first syllable of the sequence that bears the main stress. In these cases the pronunciation is ˈhaɪpə(ʊ). Examples:
hypocaust hypocentre hyponym hypostyle
Sometimes the first syllable of the sequence bears a secondary stress. The pronunciation is ˌhaɪpə(ʊ). Examples:
hypoallergenic hypochondria hypodermic hypogeal hypotactic hypotaxis hypothermia hypothetical hypothyroid
In the last two cases if the sound after the sequence is a consonant, the second vowel of the sequence is either əʊ or ə. If the next sound is a vowel, then əʊ is the usual pronunciation.
This tip was prompted by a post on Petr Rösel’s blog, so thanks to him.