Business English tip:

As for the language, never use short forms such as I'm, you've, etc. in a letter. Always use full form such as I am, you have, etc. You should avoid using informal language such as phrasal verbs or idioms. So, for example, instead of 'carry on' you should use 'continue'.

Practical tip: It's not likely you are going to write you letter with your hand, but written in a word processor, it might look impersonal. To add it handwritten look use CopyDoodles©. Check their website: www.copydoodles.com