There are so many suffixes in English language which makes it impossible for us to analyze all of them but we will take a look at those that are common and can be applied to a large number of stems to make new words.

Suffixes that carry the primary stress

Example:
Vietnam /viɛtˈnɑm/ (the primary stress is on the second syllable of the word)
Vietnamese /viɛtnɑˈmiz/ (the primary stress moves on the suffix)

In the given example above (and the examples provided below) the primary stress is on the first syllable of the suffix. However, if the stem consists of more than one syllable then there is a secondary stress on one of the syllables of the stem (in our case the secondary stress is on /ɛt/).

Other examples:
Entertain (only for verbs)
Refugee
Mountaineer
Cigarette
Picturesque

Suffixes that don’t affect stress placement in the stem

Example:
Comfort – comfortable
Anchor – anchorage
Refuse – refusal
Wide – widen
Wonder – wonderful
Amaze – amazing
Devil – devilish
Bird – birdlike
Power – powerless
Hurried – hurriedly
Punish – punishment
Yellow – yellowness
Poison – poisonous
Glory – glorify
Other – otherwise
Fun – funny

In the case of words formed with the suffix “–ish”, multi-syllable verbs always have the stress on the syllable immediately preceding the suffix “–ish”. This rule doesn’t apply for adjectives formed with “–ish”.

Suffixes that influence stress placement in the stem

Examples:
Advantage – advantageous
Photo – photography
Proverb – proverbial
Climate – climatic
Perfect – perfection
Injure – injurious
Tranquil – tranquility
Reflex – reflexive

Special case: the suffixes “–ance”, “-ant”, and “–ary”

• In words formed with these suffixes the stress is placed on the stem (almost always) if the stem is monosyllabic.
• If the stem has two or more syllable then the rule of stress placement is based on syllable structure.
• If the final syllable of the stem contains a long vowel or a diphthong, or it ends with more than one consonant, that syllable receives the stress.
• Otherwise the syllable preceding the last one receives the stress.