MIG welding, though it generates a lot of heat and harmful light, can still be absolutely safe as long as you follow all the important safety precautions.
As a first step, you should permanently position a fire extinguisher near the welding area. It is better to have CO2 type of fire extinguisher when welding. Water extinguishers may be inappropriate in a welding shop since you will be standing amidst a whole lot of electricity.
Make sure there is adequate ventilation in the welding area so that the harmful fumes do not suffocate you. Wear either a mask or a respirator if you are going to be welding for a prolonged period of time.
The light that is generated by any type of welding is extraordinarily bright and can burn your eyes and your skin just like the scorching sun if you do not adequately protect yourself. Therefore, the first thing you will need before beginning your welding work is a welding mask.
It is preferable to wear auto-darkening welding mask as it is safer if you are going to do welding for long hours or be working with metal often. Unlike manual mask, auto-darkening welding mask allows you the freedom to use both your hands to weld, and not bother about repeatedly adjusting the mask. Use a welding screen as well to protect others around the welding area from the blinding light.
Never indulge in MIG weld if water is in contact with you or there are water pools around your welding surface. This is necessary to avert all possible chances of electrocution.
Due to excessive heat, your skin and hair can burn and it therefore is necessary to wear long sleeve shirt and non-flammable long pants without cuffs. Use leather welding gloves and an effective eye shield or welding hood. Some people prefer thin gloves for welding for better dexterity of both wrist and palm - but for MIG welding you can wear whatever gloves you feel comfortable with.