I´m really busy these days so I haven´t time to write on here as often as before. You usually do things "on" the internet, so instead of using "in" like "write in my diary," you should use "on," because it's the internet. ^^ You can also say, "...I haven't had time to write on here so often," and omit "than before."

I´ll go to Cádiz next March. If you mean March 2011, you should say, "this March." If you mean March 2012, then "next March" is appropriate.

I and my friends will spend 7 days there. Or "Me and my friends will be there for 7 days." Also, in formal English, usually the speaker puts him or herself last, as in, "My friends and me." This is a good grammar check, because now you see that if you omit "my friends," "me" is incorrect, because you're left with, "Me will be there for 7 days," so you see you need to use "I" instead. ^^ Does that make sense?

This new year I will have too much work and might not get any holidays.

That is why I NEED to take a break before the hardest part of my job comes. I think this is what you meant, but I'm not completely sure. ^^;

You can see a few photos of Cádiz. Or "you can check out a few photos of Cadiz."

I think it is a nice place to stay and enjoy.

hahaha Anyway, I will tell you how my trip was on Lang-8.