Spotting The Error

These questions contain a sentence or a group of sentences broken into different parts and labelled as (a), (b), (c). Generally option (d) is No Error.
Do’s – 
1. Check Subject – Verb agreement must agree i.e singular & plural verb.
2. Check the use of Idioms & Phrasal Verbs.
3. Look for incorrect punctuation i.e. apostrophes & commas.
4. Pronouns must be checked i.e. singular & plural forms.
5. Also check any vocabulary mistakes.
Don’t’s  -
1. There only one error in one sentence so never try to look for more than one error. 
2. Never look for spelling errors & capital letter mistakes.
3. Never try to figure out how to correct the error.
4. Never hesitate to choose No Error option is you can’t find any error.
If you are facing any problems in spotting the errors using traditional approach, then you must concentrate on the answer choices and then try to eliminate them.