For the anxiety in general, get some exercise. And make sure you're breathing correctly and deeply. In slowly through your nose until your lungs are fully expanded, then out slowly through your mouth. Do that 10 times and you'll notice a difference in your anxiety. Do it reguarly throughout the day, and it'll really help. The exercise makes a tremendous difference, too.

For the anxiety-related heart palpitations, which are very common and are called PSVTs (paroxysmal supraventricular tachycardia), try this. When you feel your heart flutter, exhale forcibly through your lungs, but keep your mouth tightly closed and pinch your nose, too, so the air can't actually get out. As you exhale, you'll bear down like you're straining to cough or have a bowel movement. This is called the Valsalva Maneuver, and it nearly always gets rid of those types of palpitations. You only have to do it once when you feel the palpitations, not repeatedly.

Other anti-palpitation techniques include rubbing the neck just below the angle of your jaw to stimulate the carotid sinus or plunging your face into ice-cold water, but those other two aren't as easy or practical as the Valsalva.

Finally, be very judicious about your use of cannabis. It can definitely aggravate anxiety, and smoked cannabis isn't good for the heart rhythm. If you can find Indica-dominant strains, you'll be less prone to anxiety than you will with sativas.