The ones you rely on yourself to do all I know are more visualizations/meditations than a spell/incantation ... here's the best one that worked for me, from here, but it worked for me because it's very very detailed. Really, it's a lot of text, even if I edited some parts out that the excerpt below would still be useful, it's still long. So I hope you like reading.
"Picture yourself floating in a a 'void', an empty space. This is to get you focused on yourself without distraction. An important (and often overlooked) part of effective visualization is... do not picture your body from the third person, instead visualize the void around you, and feel both your physical body and energy body in that void. The idea is that you visualize with your perspective being in the right spot. You should not be picturing yourself from the outside. Picture yourself from the inside, like you might in a dream. Then just relax and focus on what you feel. You feel your body. You feel the energy influence on you. And you feel your energy body, which is the part of you which senses and reacts to that outside energy influence you are going to shield out.
...feel your energy, see it in your mind's eye, and feel it, feel its currents within your and even outside you a short distance. Now focus on making your personal energy glow brighter and brighter. As it glows brighter it flows through you more strongly. Feel the energy currents flowing in a rush, as you grow ever brighter. The sensation of feeling your energy should be increasing dramatically as well. If you are able to draw on an external source of energy, you could do so now to increase the energy intensity even further. Keep getting brighter till you are absolutely brilliant. Feel the energy getting very thick and very strong. Feel it building up pressure. Gathering strength and power. Keep going until your energy feels like a drag racing car, engine revving loudly at the starting line, ready to take off with great force. This 'powering up' gives you a great deal of energy to work with, and lends confidence to your will.
Now extend some of your energy outward all around you, just a little ways, extend it till it is out of arms reach, out beyond the furthest reaches of your personal energy. Some may have very widely dispersed energy extending out a considerable distance, if this is the case for you, extend this surge of energy from within out a little further, and work at pulling back in your more stretched out portions of energy body so as to be fulling inside the border of it. There is plenty of energy, plenty to extend tons of energy outward, and even though you extend it outwards from yourself a short distance, you maintain ownership (control) over the energy. The energy is still 'part of you', fueling your actions, empowering your will.
Begin shaping the energy you extended out from you into a sphere shape around you. Make it a perfect sphere, around your front, back, left, right, over, and underneath you, equally in all directions. Make it large enough to move within it comfortably without touching its inside. Make it spin if you have trouble visualizing the entire shield around you all at once, this helps some people to picture it whole while also visualizing it from the inside. Remember, in your mind you are looking outward at this sphere in all directions. If you can, abandon directional vision in your visualization and picture it all around you in 360 degrees at once as though you had eyes in the back of your head (and top, and feet) that would be the ideal way to go about it. It is not physical, and your visualization is in your mind's eye, not your physical eyeballs, so don't let your familiar way of perceiving detract from the completeness of your visualization.
Focus on your sphere. It is a complete sphere, there are no gaps in it, and it is so dense with energy that even if there were a gap it would fill itself in immediately. And make the energy so that it will not let any spiritual, personal energy, psychic energy, emotional energy, etc. influences pass through it, while physical things are unaffected by it. This is a quality which you are trying to imbue it with, there is no special trick to making the shield take on a characteristic like this. Just like you moved the energy around, and changed its shape in your visualization, now you are narrating a change in its nature. It is just another facet to your visualization.
Now make the energy even more dense, Denser than lead. So dense it is like the mass of a freight train compressed into a sphere shape around you, only a few inches thick. And then begin to make it harder. Its already very hard from its density, but now you are visualizing that the energy itself is changing into a very hard type of substance as well, shifting its state and properties. The energy now takes on a glossy finish, as it turns hard like steel. Then harder than steel. Still harder till it is as hard as diamond, but then past diamond. Till it is the hardest substance that you can imagine. Overkill is the goal here.
Make it totally opaque, totally immovable. It is, however, centered to you, so it goes where you go, but nothing else can move it. You are its sense of 'center' so the fact that it goes where you go physically does not really seem like movement at all to your shield.
Now focus on keeping it just as it is for a bit, make it stabilize as it is. Focus on making it have resiliency of form. Push on its nature to stay the same for a prolonged period of time. It is now unchangeable, unscratchable, impenetrable. Imagine that anything going against the outside of your sphere could not dent it, could not scratch it, could not pierce it, could not take any of the energy from it, its a totally sealed indestructible hollow object of energy with you inside.
Now let your focus on the shield itself diminish slightly by returning to your sense of self, surroundings, and the physical. Keep the shield in your minds eye, but pay attention now to how your energy body feels that outside influence. Can you feel it yet?
If you pay attention to all of your senses, including the physical, you still hear all of the physical things around you, but there is "something" missing from your senses. The sensation of the outside energy influence should be gone, but also a general subtle sense of isolation. Its like a a background sound has been shut off. You feel isolated, insulated, enclosed. Even if you are outdoors. On some intangible level, you feel like you are in a bank vault, cool and soundless, but not a physical absence of temperature or sound. Pay close attention to everything that feels different or missing from your sense of your surroundings...
...Whats missing is your 6th sense, if you will. Sometimes called the second sight, third eye, etc. lots of esoteric terms for it. But whats missing is all of the influences which effect your emotional/psychic/spiritual/astral energy sensitivities. And if you were in a situation where you were being strongly influenced or even attacked, then you should (most likely) feel that is gone too."
And that's a basic bubble shield, only I find the detailed instructions make it more than the usual psychic shields that for me were as effective as a soap bubble. You may also want to add a command like "stay like this for 8 hours" so you'll know when to cast a shield again instead of waiting until it loses rigidity and develops weak spots, or starts to vamp you for energy to keep itself up and protecting you.
