I keep having premonitions. Unfortunately, they aren't very long or very far into the future or past! They also happen only about once a day... For example, instead of helping my friend who would graze her knee in a few minutes, I got a useless premonition about who would kick me in class! It didn't even show the person's face! Any spells that might help my premonitions lengthen and actually be useful? Thanks.
i don't think you need a spell, you need to practice your clairvoyant abilities, and balance your chakra's. with your chakra's, don't focus on your third eye, you need to start from the root up to your crown, balancing all your chakra's so energy does not pool, instead it flows freely. this will help you with your premonitions.
for exercises you could try to strengthen it can include concentrating before you start your day, and try to have three premonitions, write them down, then check off which ones you got right at the end of the day. if you don't have caller ID on your phone, try visualizing, or sensing who is calling before you pick up. [doesn't if it's normal for a person to call at certain times] another one that works well is if you keep a dream diary, and interpret your dreams. becoming a stronger dreamer it has been said strengthens our mind and increases our clairvoyant/psychic abilities.
You could find a way to grasp the mindset or feeling that induces premonitions and push it away when not needed. Controlling a mindset like this is rather important to supernatural pursuits and I am honestly surprised you developed such ability for divination without it. Here I can even recommend the IIH, or at least the first few stages in thought and body control. That should help you to control any episodes you may have.
Try controlled breathing, pay attention to the in and out breaths, listen to the rhythm and start consciously controlling the timing. Try it for just 5 to 10 minutes at a time at first...you can also do this while you are having one of your experiences, and it will help shift the consciouness back where it belongs. This will allow the mind to rest and should calm your system a bit. You just need to get better control over yourself...and do NOT go into fear. Fear is one of the most damaging emotions one can hold.
With time the goal in premonition is to be balanced enough to observe what is being played out, not to let the emotions pull you into it...detachment. Many times it will be observed in the 3rd party position.
also try meditation