For a beginner, the skill is pretty umm.. common, in my opinion, but with a sense of creativity. Cause, speaking honestly and unambitiously -- I had better skills for a 3-month photoshop user and artist.
I assume you're using Photoshop.
Practicing your typographic skills is very necessary, man. You have a problem in choosing a color, as far as what I notice. One way to have a fitting text in your signature is create a text first; use a fitting font. Afterwards, create a new layer and place it above all the layers. Then hide the layer of the text and click the 'Image' tab -> and click the 'Apply Image'. Next, place the layer with applied image above the text then use the layer as a clipping mask (Right click the layer (on the layer's name) then click clipping mask). Was it that hard?
It's okay, considering you're a beginner, and it's part of the learning process.
If you can't understand my explanation, you can search this on google:
Photoshop - Inserting Clipping Masks
I can't create screenshots, I apologize.
Know any movies? Of course, I assume you do (you're a modern humane). You also lack lightings and light sources in your artworks. You can apply one by creating a new layer, then place it above all layers, afterwards, apply image (Image tab -> Apply Image) then use the Lighting Effects filter (Filters -> Render -> Lighting Effects) then lower the opacity if needed.
I also advise that you find tutorials on the internet and download .PSD of the signatures or artworks.