noredink.com (by clicking the link you will enroll in my class on noredink and receive all of the practice assignments)
varsitytutors.com (main list of all tutorial modules--very comprehensive)
SENTENCE COMBINING
PARALLELISM
PRONOUN-ANTECEDENT AGREEMENT
SUBJECT-VERB AGREEMENT
ADDING SENTENCES & OTHER INFO
DELETING SENTENCES & OTHER INFO
WORD CHOICE, STYLE, AND TONE
IDIOMS & WORD CHOICE
COMMAS FOR INTRODUCTORY OR INTERRUPTING PHRASES