Gmail by default adds dashes “- -” line before the signature. Also, the signature text color becomes grey automatically. You can avoid this problem with the help of little known Gmail lab feature – Signature Tweaks.
To remove dash, follow these steps –
1) Go to Labs from Gmail Settings.
2) Start searching for ‘Signature Tweaks’ on the lab page.
3) Enable the feature from the radio box.
4) Click on ‘Save Changes’ at the bottom of the page.
Now, there will be no dash or greyish text in your signature. Along with this advantage, your signatures will appear just below the bottom of your replied mail and after complete mail.
On a personal note, I recommend to use Wisestamp for making any signature related changes. It’s free and you can use colored text, images and links in your signature.