I used Photoshop to create my signature image. I uploaded it to Photobucket as you need a URL label in order to use it in Blogger.
The tutorial which worked for me was from the blog where I located the background template for my blog. http://blo64rt.blogspot.com/search/label/How%20to%20add%20own%20signature. Follow these steps and hey presto, you have a live personalised signature!
One thing that I did find was that in a test post, there was a white box surrounding the signature. I decided to edit my signature but no matter what I did, or how much surfing on the net I did I couldn't create a transparent background.
I took a screen shot of one section of the blog background where the posts feature and saved it as a jpeg. I went back to my original Photoshop signature file, added a layer and used the paintbucket tool to select the colour from the screenshot jpeg. I filled the background with this and now have a signature background that blends in with the blog background template. I then repeated the steps to upload this file to Photobucket to get a URL and just replaced this in the settings.
I am no expert, but if I find something more effective and not complicated I'll share it!
Have a great day,