theres about a million posts about it, but frankly the easiest way to do it is to relax your whole body, part by part and visualize a place in your mind where you feel completely at ease and relaxed.
construct the place bit by bit and add details, it will let you active mind do something but at the same time has a calming effect.
youre creating a "sacred" place some people would call it. but it is a safe and good place that you create that you can go to anytime and as you construct it, then over time you will find it easier and easier to get into that very and deeply relaxed state.
focus on your breathing quite a bit. inhale through hthe nose and exhale through the mouth very deeply. your stomach (really your diaphragm) should rise and expand.
At a certain pont make an effort to hear your heartbeat and kind of focus on that.
when thoughts drift into to your head try not to connect them. just dismiss them. So if Sally pops into your head, don't connect her to the lunch you have tomorrow, just dismiss the intial thought and go back to focusing on the inside of your eyelids, or making your special place of your breathing
be PATIENT and don't rush yourself. there is no rush for anything. just let everything happen as it is going to happen and if you can relax for 10 minutes on Tuesday, go for 15 minutes on Thursday.
just relax and let go.
there's tons of stuff including guided meditation techniques out there and some stuff resonates with you while others might not.
but visualization is a key component to spellcraft, imho, and once you got that down i imagine your headaches will go away and youll experience a lot of success with your magick
Best of luck and you know, its always good to hear of successful progress so keep that up too if you want!