You protect yourself by trying to stay aware of your own vibrational setpoint and what you are giving your attention to. When you are in a feel good place negative entities or energies cannot influence you unless you choose to let them. By consistently monitoring your own thoughts you can choose to change them and thus change your vibration - cultivating an immunity to the negative energy.Persistence and focus are the keys.

You protect yourself against dangerous entities by not attracting them, and by not giving them the voice of your mind, in the first place.

As Abraham-Hicks once said, "Man invented the devil."

If they are ''bad guys'' you can get help form ''good guys''. if it's negative energy, use positive energy. if you want general protection, I would suggest visualization and/or charging material things ( that represents personal spiritual value to you ). like a special rock or a crystal. use something that you usually keep close to yourself or the one you wish to protect. all these ''rituals'' are very known in magick. but the problem is, new age writers and gurus, never talk about it. even though, it's the only practical way to perform or practice what they preach. the law of attraction for example, is old news in magick. and it's not well understood even today. so if you really want to get into this, read about magick. forget about the complicated stuff, go right to the core and you will find everything you want to know and anything you need. just stay away from contacting spirits or creating/using beings from other dimensions. stay with controlling energy and using your own mind powers.

As all the others so far said - do not be overly concerned. I would re-emphasize the way Stingray termed it with their differentiation between "protecting yourself" and "feeling secure." They come from different states of mind.

As Adel mentioned, there are 'means and means' for this - many gone into in "magic". You likely have no interest in getting involved in that - and I do not believe this site is really focused on that area of investigation. But just for an example, since I like to be somewhat thorough...in one particular grimoire, a Blood Stone is recommended as a protection against the so-called "Fallen". It is wrapped in linen and kept on the person. It is meant to act as a shield (in practice, it is actually observed more as making you unnoticed). There is a simple ritual that many use before using it - and there is symbolic significance behind it.

However, even in ritualized magic (where external items are often assigned various powers that can potentially be utilized...though something that is actually only a fraction of the truth IMO) - in the above case, that dealing with entities purposefully...the main item of protection is -always- the 'magical circle'. That circle's power, is in the persons realization that a circle 'has no beginning and end.' In other words, that it represents God - and in their standing in the center of it, that they are unified with the All Good and thus - not even the "Fallen" - can harm them in any manner (and they take it further, that they must obey them). So you see in practically - all - systems I have come across the main point is what others earlier mentioned...your mental focus.

I will also add as an aside - the thing you mentioned above about preventing others distracting you is a possibility. That is something often done with those who might label themselves as "psions". It is possible to set up 'constructs' around an area that will defer others away - or send some alert to you. (Although, in the case of being busy - you may be too engrossed to actually notice the signals)

But again...these are rather different approaches - and I never expected to go into them here, nor think I ought to. Some people, even those more 'enlightened' such as you can find on this site, are often still intriguingly adverse, even fearful of "magical" approaches.

The spider web type protection that you mention exists in the form of a radionic graphic device known as "le bouclier" (the shield), here is the reference:

http://www.servranx.com/Products/Graphiques/DE-RADIONIQUE/N%C2%B0-15---Le-bouclier.aspx

It is designed to protect against all undesirable energies and entities and is very easy to use. Just place a witness (sample of saliva, blood...) of the person to be protected in the center of the graph for ten minutes which will provide a complete protection for the following 36 hours. It can be obtained from Editions Servranx e-mail info@servranx.com

simply by having no darkness in you and fighting with all your might. and if it is not enough simply say the truth with no fear of death god is in me i am in god kill me if you want but you will be destroy for ever. experience and enjoy.

it worked against the old hag so it should be good enuff.A hag, or "the Old Hag", was a nightmare spirit in English and Anglophone North American folklore. This variety of hag is essentially identical to the Old English mæra — a being with roots in ancient Germanic superstition, and closely related to the Scandinavian mara. According to folklore, the Old Hag sat on a sleeper's chest and sent nightmares to him or her. When the subject awoke, he or she would be unable to breathe or even move for a short period of time.In the Swedish film Marianne,the main character suffers from these nightmares. This state is now called sleep paralysis, but in the old belief the subject had been "hagridden".[9] It is still frequently discussed as if it were a paranormal state

http://en.wikipedia.org/wiki/Hag

You wake up unable to move, barely able to breathe... you feel an oppressive weight on your chest... and you sense some evil presence in the room... The old hag strikes!

http://paranormal.about.com/od/humanenigmas/a/Old-Hag-Syndrome.htm

that thing feeds on fear and attack you when you are trap in the body before you exit. do not fear have no fear of death.

Do a visualisation of you being bathed in bright, heavenly white light. This will protect you.

Then, ask archangel Michael to be by your side and protect you (by just saying that out loud).

I do both of these before I go out at night, and I've also printed out a small picture of Michael which I carry around in my pocket wherever I go.

I also agree with the answer based on vibrations, thoughts and LOA, but this is another technique pyschics use to preserve their spiritual energy and protect themselves from harm.

I agree with Stingray if you think you need protection and do rituals or whatever to protect yourself you will allways have the need for protection for you will create your own reality. If on the other hand you believe that you are allways protected no matter if in your physical body or astral or whatever and you impres your subconscious with this belief and become firm in your strength and loose your fear you will create a reality where negative entities and energies can't bother you.

Believe in yourself and be strong and firm and pretty soon you will lose the fear and be victorious.

for what it may be worth,
the stronger the light side (white magic) the lesser the dark side (black magic),
do not let negative elementals feed off you,
your conscious decision to do such may be supported by utilizing amulets;
but the end result will be your mind directed by your will, guided by divine spirit