Step 1: First Things First.
Now that you have that in mind you need some inspiration. What do you want to draw? I know a mushroom! Grab a digital camera run outside and snap a photo. Once you have that load it up on your computer and start your favorite image editing software. Bonus points if its MSPaint. FYI anything created in MSPaint that appears to look good can have a x10 coolness added to it for being created in MSPaint. Thus increasing your appearance of talent. I however will be using photoshop. If you want to follow along use the nice photo of the shroom I snapped earlier today while geocaching.
It's best to start big and then before you finish shrink it.
Step 2: Color by Numbers
Once you have a basic outline done your going to want to create another layer. This will be your color layer. Just grab your paint brush and paint solid colors. Don't worry about shading yet. Once you have the color layer done it's time for the shading. This is what makes you appear to have talent. Sure people with the artistic capability of a 3 year old can color inside the lines but how many 3 year olds do you know that can shade? This is what sets you apart from the rest of the runny nosed nap taking graphic artists.
Now shading isn't as tricky as it looks. What you want to do is look at your picture. Do you see a shadow? or a dark spot? Using your paint brush set to black with an opacity of 5 or so ish % just start coloring. 5% is just enough to make a slight noticeable difference. If it needs to be a little darker go over it again. I found the best way to fade the shading is to start where you want it darkest. Make your shade. Then go out a little and shade some more making sure to re shade the previously shaded part. Keep doing this till you get the center as dark as you want.
Background. If there are elements in the background that you must have do the same procedure you did with the main focal point. Adding background elements however requires a small bit of talent. Proceeded with caution. Otherwise, and to keep it simple, use solid colors that blend or contrast the image. Take a look at my images below for some ideas.
As you get better and begin to develop talent you can remove the original photo from the whole ordeal. Instead look at something and later go and draw it. It takes practice to get talent, but why wait just do what I do and appear to have talent from the git go.
To get a better feel for the info I have laid down please watch the complimentary video.