Can I join? Any way, I don't think we need to do this, but, because @Zander_Eldercraft did something similar, this is a list of some of the most commonly made grammatical errors:
1.1. Distinction between A/An
1.2. Use of “A” before a noun has been introduced
1.3. Use of “A” for singular, non-specific, countable nouns
1.4. Use of “The” for superlatives
1.5. Use of “The” for specific, countable, plural nouns
1.6. Use of “The” for specific, countable, singular nouns and uncountable nouns
1.7. Use of Zero Article for non-specific, countable, plural nouns
1.8. Use of Zero Article for non-specific, non-countable nouns
2. Subject and Verb Agreement
2.1. Active Verbs
2.1.1. Use of subj.-verb agreement with the present tense
2.1.1.1. Simple
2.1.1.2. Progressive
2.1.1.3. Perfect
2.1.1.4. Perfect Continuous
2.1.2. Use of subj. -verb agreement with the past progressive
