Make sure that the butter is soft enough to mix easily with the other ingredients without clumping up too much.
Once the butter is soft enough, whisk it in a large bowl until it forms a smooth paste.
Add the garlic to the butter and whisk it together until you mix it evenly.
Add a bit of parsley and/or chives according to your tastes and preferences, and whisk everything together.
If your butter was salted, then you are done with the process. However, you might need to add a small amount of salt in case the butter is unsalted. Do this according to your taste so that you do not add too much or too little.