The following brief passage from a personal development blog yields an excellent example of how to replace formal and stiff writing with a more casual and conversational tone:
Procrastination is a solution to a short-term problem, even if it is a bad solution. As long as we do not have a better solution we will stick with the one that we have.
This sentence is grammatically correct, but the formal tone and convoluted style simply isn't suitable for blogging. Consider something like the following instead:
Procrastination is a bad solution to a short-term problem. And until we find a better solution, we'll stick with the lousy one we have.
Notice the differences:
1) I rewrote the first sentence to make it simpler and more direct.
2) I omitted several needless words to improve the flow of the sentence, including the long series of little words in the second sentence (As long as we do not have) which I replaced with the more direct until we find.
3) I added the word And to the beginning the second sentence for a more conversational tone. This is improper style for formal writing, but it's perfectly suitable for casual writing.
4) I added a contraction (we'll) and used the highly casual word lousy to make the tone still more informal.
The result, while not perfect, is easier to read and considerably more casual in tone.
Style is often a matter of taste, and there may be levels of informality that you'd prefer to avoid. For example, you might consider the word lousy to be inappropriate. It's okay if this is your view--simply choose another word and move on. However, I hope it's clear to all that if you write in an excessively formal tone you will always struggle to find readers.
This post is gratefully dedicated to Maria Machon.