It is amazing what you can do if you put your mind to it. And it is amazing how easily you can defeat yourself with the wrong attitude before you even get started. Why not foster a belief in yourself? Start small and work your way up. One success will boost your self-esteem and result in more attempts. Some of these attempts will undoubtedly end in success and this will in turn lead to a stronger self image, greater skills and more knowledge.
So, you have no experience. So, you have no formal training. These days there are so many how-to books in the library and so much information on the internet, these excuses are unwarranted and will only hold you back.
Keep in mind, too, that sometimes not following the prescribed method of doing things can work in your favor. You just might be the person to figure out a better way to get from here to there. You could be the one to build a better mousetrap.
And, don't view setbacks as failures! If you try something, but don't have the full success you hoped for, your efforts are learning experiences no matter what else they produce. At the very least, you have learned what doesn't work.
Read all you can on the subject of your desire. Find an expert in that field, seek this person out, ask questions and above all, listen to his advice. He may be able to steer you away from pitfalls. However, if he has nothing but criticism for your plans or a negative attitude about it, don't let this person crush your dreams.
If there are differing opinions as to the best approach to follow, consider gleaning ideas from more than one source and blending them for your own use. If no one has ever done exactly what you want to do, experiment with different techniques, make adjustments as needed and try again.
It wasn't that long ago that people were forced to know how to do for themselves. If your great-great-grandmother needed a dress, she made it. She might even have woven the cloth from wool she spun herself from sheep she raised herself. Were your ancestors experts on all subjects? Of course not, but through first-hand trial and error they learned enough to get by. You come from good stock. If your ancestors could teach themselves the skills they needed, you can, too.
Consider this - everything that has ever been built by man began by somebody with an idea, following his own mind, giving it a go and risking the possibility of failure. Somebody was the first person to do everything people do. Why not you?