Common errors made by new writers.

Sentences that begin with gerunds are often weak sentences as they are frequently in the passive voice:
check out this lesson in gerunds:
Check out dialogue tips and punctuation here.
Repeating monotonous sentence structures - there's a good example here of Stephanie Meyer's monotonous sentence structure.
Joining two independent clauses without using correct punctuation or sentence modifiers - here.
Over-reliance on adjectives and adverbs rather than verbs, which are the muscles of writing - this is simply a matter of going through your own work and highlighting adverbs and adjectives and seeing which ones you need.

Do go through your work with these problems in mind. Happy Easter!