There are a lot of spells and rituals that involve drawing (or sewing or otherwise physically creating a representation of something). I am blessed to be artistically inclined, although I haven't had formal lessons in ages, I do consider myself pretty artsy. Most of the time I can make pictures of things that make me happy, and while I don't think I am quite on a professional level, I don't stress out when I have to draw or craft something.
But I know that a lot of people don't share this gift. I know my son always says he is horrible at art, and even for school projects hates having to do anything that involves drawing (even when the quality of the art isn't in any way being judged). It doesn't matter how many times I reassure him that it is the effort that matters and that his pictures are fine, he still feels frustrated when he tries to draw something, especially if he is trying to copy a symbol from somewhere.
When it comes to using artistic skills in workings, I feel very strongly that the quality of the work itself is not important. What is important is the intent, focus and emotion put into the crafting. The purpose of creating a symbol to represent something is to activate the child self, the younger self, the subconscious mind. This part of you doesn't care about perfect, it sees perfection because it sees the essence of a thing, not the specifics. So if you make an apple out of clay and it looks more like a lumpy ball, your child self sees the apple anyways, because it believes!
I think it is vital to approach sacred art in a playful manner. Let your inner toddler out! Don't worry about making a mess, about coloring inside the lines or even about making things the right color! If you want to create harmony in your house, and feel that lavender makes you feel good, draw your family and color them lavender!
Think about it this way: if you were handed a picture by a kid, who told you they made it 'just for you' and asked you if you liked it....most likely you would tell them it was great and wonderful and you absolutely loved it! If it looked like a pile of green spaghetti but they told you it was a picture of their mommy, you would tell them it was beautiful. Treat your inner child with the same indulgent love! Embrace the pure joy of creation, the letting go of expectations and of letting your mind's eye create.
Put away the fancy pens and break out the crayons. Grab some paint but no brushes and use your fingers. Stop trying to fix your 'mistakes' and just roll with them. Draw stick figures with no legs or make dolls with no faces. If you can't draw hands, don't!
But most importantly, have fun with it. Sing while you create. Name your creations, talk to them, and tell them what they mean to you and what you want them to do.
If you are having trouble getting started, go and grab a piece of plain white paper (or lined paper, or whatever kind of paper you have, you can even take an old bill or magazine). Grab some brightly colored markers or crayons....nothing fine tipped or fancy, just something that makes color. Don't draw anything, just scribble. Pick colors based on how you feel. Let your lines show your mood. Try this on different days, when you are feeling differently. Look back at your pictures and see what they make you feel.