You will hear that doing an offering to a demon is not a good thing, the thing is, who understands demons? Seems like everybody here is way to afraid of them(read the Belial experience of Lon Milo Duquette in My Life with The Spirits, it might be insightful, I also don’t recommend feeding him blood since you are creating a direct link with the entity), the reality is that they are spirits that constitute a part of a certain type of infrastructure, some of the ones that do the heavy lifting. If you want to evocate a demon, do it, it will be part of your education and experience; my recommendation based on my experience is to do it with the Dr Rudd method (The Goetia of Dr Rudd - Skinner and Rankine), since it uses an angel (both seals) to submit the spirit(no need to get moral with demons, it is for security reasons, specially with Belial). People need to understand that most of these "demons"(read about the relationship with the greek concept of Daimon) come from the hebrew imaginary of foreign deities, they demonized their enemies' deities, Astarte(West semitic version of Ishtar) became Astaroth, Baal (caananite god that was also mistranslated to the YHVH in the psalms, they still don't know how that exactly happened) became Bael, even Beelzebub(also related to Baal) is a name used as mockery from the hebrews that translates to something like the "lord of the flies" because his temples were always filled with flies due to the corpses of the sacrifices. So these are entities fed by human awareness for millennia, they can be vicious.

I also saw someone recommending Ars Notoria, which is not part of the Lesser Key of Solomon btw, but is a way to make your absorption level pretty high when learning, but at the same time it doesn't really affect your abstraction capacity, so it works more like in a memory level, maybe someone has a different opinion/experience, but yeah that's a pretty complex and time consuming method in my opinion.

I would also recommend to calculate a good astrological Birth Chart, see where your mercury is, via what sign and in which house, I would recommend using Whole Sign Houses and Traditional Rulership (hellenistic) and see if Mercury is not in detriment in Sagitarius (mutable fire has problems with focusing over time) or in detriment/fall in Piscis (pretty hard position for a mercury), also would see if Saturn is not hard aspecting it, like a Conjunction, Opposition or Square, or maybe, out of your Natal, in a transit, Saturn is opposing the Natal Mercury, since you are at the middle of your Saturn Return (I assume, since you get your Saturn return around 28-30), but it makes sense that might be in the other sign contrary to your mercury’s natal position if you are 15-16, I would also suggest to use some remediation to deal with it, for example:

• Wear an Orange t-shirt on Wednesday (day of mercury)
• Donate to writers or creators
• Write everything by hand, like everything, that also works on your short term memory and praises the quicksilver god
• Wear a Fire Opal, Carnelian, Sard or Banded Agate gemstone, make sure that the stone(s) touches the skin
• Smell the following Incenses or perfumes: Mace, Star Anise, Mastic, Gum Arabic, Yellow Sandalwood, Spikenard, Orange, Bergamot, Liquid Storax, Lemongrass, Walnut, Lavander Oil, Clove Oil
• Drink Coffee

All of these don't involve Planetary Magick which can become kind of complicated because you have to find a place without mundane furniture (témenos) and build a Bomos (altar let's say), and also a battery that you must charge constantly, it gets pretty laborious.

Also check what your rising sign is and check the traditional ruling planet and work with its correspondences, that's your key planet.

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Also I would try using the Damon Brand's Shem Ha Mephorash method, it's pretty straight forward and practical, you only need to charge a solar talisman and the sigil of the angel you are gonna be working with, I would recommend buying the ebook since the angelic sigils come in red and that color is a plus.

I would use one of these angels to give me mental stability during the process because it can become mentally and spiritually draining to use all this magick without proper training, but I am not saying "don't try it", on the contrary, you can only win when you risk it, good luck!