First of all, it is necessary to understand that the faster you act, the better is the prognosis of the affected person. You should do some very important things without panicking and distressing the poisoned individual. 

Secondly, you have to remember that the first aid and the medical aid are quite different categories and there are different approaches and people involved in them. To save your relative, friend or neighbor, you have to know how to give him a first aid. The medical aid is a priority of people with medical qualification and it is you task and duty to transport and provide medical help for the victim as soon as possible. Therefore, the best first aid kit you could have are your car keys or a telephone. 

Dos, or Suggested Actions
1. Removing the poison from the entry. It is not always possible but you can do the following: 
   1.1. Skin contamination 

• Wipe the affected area gently and precociously with a cotton dress or a cotton wool ( make away with the contaminated materials after the procedure to avoid further poisonings)
• Rinse with fresh water (or sea water in some marine animal poisonings)
• Carefully remove the clothes of the victim for a danger of  still remaining  poisonous agents

   1.2. Eyes’ contamination- wash with fresh water carefully and dry gently.
   1.3. Indigestion- provoke vomiting if the victim is conscious and without seizures or bleeding from the digestion system
   1.4. Inhalation of the poison- take out the affected person from the toxic area to fresh air
2. Restriction of the poison dissemination in bites/ stings
   2.1. Splint the affected limb
   2.2. Hold the affected limb in horizontal position (on the heart level)
   2.3. Tighten the affected limb with a tourniquet or a compression bandage above the bitten/ stung place (This method is advisable mostly for poisonings of insects, arachnids and marine animals. Although it was widely used also for snake bites for many years, recently it was rejected because of the risks of severe limb damage)
3. Give lots of water or other drinks (NO ALCOHOL) to the victim if possible. 
4. If necessary, apply cardiopulmonary resuscitation- maintaining adequate breathing and heart activity (indirect heart massage) 
5. In people known to have allergy, use his/her own antiallergenic pack if prescribed by a physician (commercially available in many countries)
 

Don'ts, or What to Avoid
1. Do not do anything except for the first aid recommendations 
2. Do not apply any kind of potentially harmful herbal and folk remedies
3. Don’t treat the bitten place with anything but water (sea water if necessary)
4. In case of a snake bite:

• No ice 
• No tourniquets or compression bandages 
• No mouth, vacuum pump or syringe suction
• No incisions (cuts), excision or amputation of the bite site
• Don’t take the snake for identification if you are not sure it is dead. 
• Don’t kill the snake if it is still alive

5.  In case of insects’ and spiders’ stings:
Do not give painkillers to a person known to have allergy