You should try to avoid clichés in your writing like the plague. If your writing is thick as thieves with clichés that are as old as the hills, it will sound unoriginal and mark you as an inexperienced writer. But if you happen to find yourself doing the same old song and dance, there is an easy fix.
Clichés are often metaphors or similes, so most can be replaced with a different analogy.
Clichéd: It was the best thing since sliced bread.
Corrected: It was the best thing since Radiohead.
If you are having trouble avoiding clichés, the best solution is to read more. The more you read, the more turns of phrase you will be exposed to and the more variety you will be able to incorporate into your own writing.