thee (pronoun): you (old English)
thou (pronoun): you (old English)
art (verb): are (old English - verb 'to be')
temperate (adjective): mild; pleasant; warm
do shake: note use of auxiliary 'do' in present simple positive. This is unusual but perfectlynormal for stress, politeness or poetic effect.
bud (noun): first growth on a plant or flower
lease (noun): period, time, duration
hath (verb): has (old English - verb 'to have')
eye of heaven: Shakespeare is referring to the sun
complexion (noun): colour; appearance
fair (adjective): attractive; beautiful; handsome; lovely
decline (verb): to become less; to decrease
thy (adjective): your (old English)
eternal (adjective): endless; everlasting; infinite; permanent
fade (verb): to decrease; to decline; to dissolve
brag (verb): to boast; to tell everybody triumphantly
wand'rest (verb): old English - verb 'to wander': to walk without direction; to roam
shade (noun): shadow; darkness; gloom; obscurity
growst (verb): old English - verb 'to grow'
so long: as long