10. Necessary - Make sure you're on top of the 'c' and 's' usage.
9. Tomorrow - One 'm' and two 'r's!
8. Weather/Whether - Cloudy skies/doubt and choice.
7. Hers - Never needs an apostrophe. Forget about it!
6. Effect/Affect - Tricky one! Check a dictionary and apply in context.
5. Its/It's - Belonging to/contraction or short for (use apostrophe for missing letter).
4. Their/They're/There - Belongs to/they are/place or postion.
3. Your/You're - Belong to/You are.
2. A lot - Never 'alot' and never will be! Two separate words! Very common.
1. Speciality - Most people misspell this, leaving out the 'i' between 'l' and 't'.