You could call me a member of the Grammar Police. Although I hardly ever correct people's grammar anymore I always want to and even though I make some errors sometimes I hate it and usually correct them quite quick. However some people need a starter lesson in grammar (you know who you are) so here you go.
To, too, and two
People seem to get this mixed up, mainly to and too.
To - 'I am doing this because I want to.' 'I am going to have a drink...'
Too - '... and I am going to have a sandwich too.' 'I have too much to do today.'
Two - 'Actually I am going to have two sandwiches.'
Too many times I see these three getting totally mixed up. Too can be used in the same as as also, as well, in addition etc, or to show an extreme. I see this sort of thing quite a lot... 'I went too the shops to get to pints of milk'. Bah.
There, their, and they're
This is a good one. These have very different meanings and I see them being used wrongly rather too often.
There - 'I am going over there.' 'There is no money in my bank.'
Their - 'I like their house.' 'It's their problem, not mine.'
They're - 'They're not going to like this.' 'They're going to be here soon.'
They're means they are, which is why there's the apostrophe, and seems to be the one that causes most problem. Also there and their get mixed up quite often. Bah. Take this test and this test. If you get less than 17/20, double bah.
Your and you're
Similar to above, very commonly used wrongly.
Your - 'I like your car.' 'This is your fault.'
You're - 'You're very annoying.' 'If you don't look at the map, you're going to get lost.'
You're means you are, which is why there's the apostrophe. Saying 'your doing something wrong here' is bad. Bah.
Its and it's
This is an easy one to get wrong actually.
Its - 'I got a new computer and broke its monitor.' 'The dog lost its ball.'
It's - 'It's a great day today.' 'I don't think it's going to work.'
It's means it is or it has, which is why there's the apostrophe, and its is possessive. 'Its good to be here' and 'the tyre lost it's pressure' are wrong. Bah.
I has always got to be a capital if it's about you.
I hate this. I've forgotten something. I'm tired. I'll do it later. I'd like to do this.
Not seeing I with a capital in these cases is unforgivable. Bah.
That's about it for the common ones.