Test your mixture by dropping a few drops on a plate or wax paper and letting them cool. When they are thoroughly cool, test the consistency. If the consistency is too hard or too soft, simply add more beeswax to make it harder, or more shea butter and/or coconut oil to make it softer. Experiment until you get a texture that you like.
When you're happy with it, pour your mixture into a container to cool. You may wish to strain your herbs out, though it's certainly not necessary - a matter of personal preference. Let your balm cool to room temperature (feel free to put it in the refrigerator to speed this process up), and enjoy.
If you've had your balms a while, you might notice that they develop a lumpy texture over time. This is caused by the components separating due to melting and resolidifying as the temperature fluctuates. If this happens, simply scoop it all back into a double boiler, re-melt and re-pour everything. After it solidifies, you'll have a nice, smooth texture once again.
A note about common sense: This is going on your body. Make sure any herbs and oils you use are safe and will not cause irritation or other unpleasant reactions. Just because it's a plant does not mean it's safe. Use your head and support it with research.
Taking it further:
This method can also be used to make lovely, luxurious lip balms. For lip balms, I use only two ingredients for the base: beeswax and coconut oil. I save old lip balm tubes to refill or purchase them on Ebay, or sometimes I just use little containers that I have sitting around the house. Since you want a much more solid consistency for lip balms, you'll use mostly beeswax with a smaller amount of coconut oil - probably more like a 5 to 1 ratio. I don't add herbs to lip balms, but if you choose to, you'll definitely want to strain your mixture unless you want people pointing out all day that you have something on your lip! I like peppermint oil in my lip balms - it gives it a wonderfully tingly feeling when I put it on my lips. To lip balms, you can also add to your melted mixture a small amount of lipstick to give your balm a hint of color. Magically enchanted lip balms are great for spells dealing with confidence, attraction, beauty, communication (since the words have to go over your lips), and sexuality. As an added bonus, the cost to produce these lip balms is significantly under the cost of good quality store-bought lip balms - I like my formula better than Burt's Bees (my previous favorite), and well under a dollar's worth of materials can fill lots and lots of tubes.
The balms can be used in a number of ways. You can draw symbols on your body with them, anoint your chakras, or just put them on pulse points so that your body radiates the scent you infused into the balm. A favorite use of one of my balms, my "great first impression" balm made with herbs and oils of the Sun and Venus, involves rubbing some thoroughly into my hands before meeting someone, concentrating the energies of these two heavenly bodies into my hands before shaking theirs. I use my "fix it right" balm on my hands in a similar manner before I attempt to repair something. I use my "essence of inspiration" balm on my forehead before writing, painting, or other creative activities, and I use my "friend to the fey" balm all over before interacting with the local fey. I also use this method to make flying ointments, which I use all over my body to assist in spiritual travel. If you do choose to make a flying ointment, be especially careful about the recipes you read - many of them contain toxic plants.
I hope you enjoy making your own balms. I've found it to be a rewarding way to practice magic, and have worked a number of successful charms through the use of balms. Share your results with me - I'd love to hear how yours turned out.