How to Proofread Effectively

1. Give it a rest.
2. Look for one type of problem at a time.
3. Double-check facts, figures, and proper names.
4. Review a hard copy.
5. Read your text aloud.
6. Use a spellchecker.
7. Trust your dictionary.
8. Read your text backward.
9. Create your own proofreading checklist.
10. Ask for help.

Details: Top Ten Proofreading Tips - How to Proofread Effectively - Editing Essays

More practice:

1. Proofreading Practice: Commonly Confused Words - Recognizing Homonyms and Homophones - Bill Bryson's Cows - Distinguishing Confusables

Proofreader marks practice: 

• Day 1 – Introduction to Common Proofreading Marks
• Day 2 – Practice
• Day 3 – Proofreading Millionaire
• Day 4 – Proofreading Quiz

Automated Proofreading: (paste a text here)

1. Grammarly | Instant Grammar Check - Online Proofreading