I just found an interesting infographic made by Copyblogger, one of my favorite blogs out there that teaches many useful tips to write good blog posts. This infographic talks about 15 most common grammar mistakes that if we do that, it will make us look silly. Since Copyblogger is written not for people who just start to learn English, I assume that these mistakes are common even among native English writers.
Honestly, I found some words that are listed there sometimes confusing for me like the