Only getting SP

Hi, just began trying LD after having done it when i was younger, not knowing what it was or why i did to start it. The last days i have arrived at the SP stage every time, vibrating feeling starting at my feets and then the whole body. I try laying still all the time, but its just goes away. One time i felt my body vibrated for a long time, 10 minutes? and i just got kinda bored lol.
I know this requires patience and learning.
One question, after i failed, i tried again with no succes. Can´t remember how far i got then. Is it "impossible" to try again after one fail?
I wake up a few times a night after i began this. I have almost always slept throughout the night before trying to LD.
One day i got a mild headache the day after? Can this come from trying to LD?
Now i have began to wake up 5-6h after sleep to try then also.
Also tried in the afternoon, but only came to SP stage there also, maybe felt "a litt less SP" then when going to bed.

When you become paralyzed and start vibrating like that, you are almost there. There is only the last, critical step of entering a dream. You may get several waves or cycles of vibrations, so don't worry if they stop. Just take a deep breath, keep doing what you were doing, and the feeling will come back.

When you feel like your vibrations are solid, not fragile or fleeting, try to enter a dream. One good way to do this is to imagine the feeling of your paralyzed body moving through space. Imagine swaying back and forth like a hammock, or rolling to the side on your bed. The goal is to roll your dream body right out of your paralyzed real body.

If that confuses you too much, or causes wacky body distortions, try imagining a whole new scene. Pick something easy, such as a vivid memory of a familiar place. Imagine, as if you are daydreaming, an activity in this familiar memory place. Make it physical, involving movement. For example, you can imagine running down your street, your body bouncing and your feet pounding the pavement. Or, you could imagine yourself standing in your living room, running your hands against the wall, feeling the texture. Or maybe walking through your house, opening doors.

Really focus on the physical feelings so you create a new dream body for yourself. Ditch that lame "real" body back in bed.