QUESTION: How do I use crystals to benefit me? For my anxiety or to find my soulmate?
MY ANSWER: Ultimately, the answer is: until you get the desired benefit. That sounds disheartening, though, so let's look at interim answers.
The longer a stone is in your aura, or energy field, the longer you will be exposed to its energy. The more of its energy you are exposed to, the quicker you may attain your desire or find something even better for you.
Some ways to keep a crystal's energy in your own energy field are carrying a piece, meditating with it, wearing it in jewelry, keeping it in your environment, and using a crystal grid created for your assistance. If you really want a power punch from the stone's energy, you could do all of them.