my first Japanese teacher had a great mnemonic device for remembering the conjugations for the て form. The conjugation depends on the last character of the verb. Just read the following as a poem:
う、つ、る:って
む、ぶ、ぬ:んで
う:いて
ぐ:いで
す:して
Make it past tense:
う、つ、る:った
む、ぶ、ぬ:んだ
う:いた
ぐ:いだ
す:した