This is just a quick and simple guide to help people insure they install their decals on a good clean surface so that they last the longest and look the best. Please note I am not the best writer, I was a math geek in school and not the greatest at English. So that said any typos I am sorry and just let me know!
First make sure you have a dry place and no wind to install your decal.
Make sure to prep the area, this is the most important part of installing a decal! If you put your decal or sticker on a dirty surface, it will just pick that dirt and grim up like a lint roller does your shirt, those aren't so sticky after you use them are they! So lets make sure the area is nice and clean so that it can adhere to where you are going to place it.
You can use soap and water, rubbing alcohol, or any other fast drying cleaner. My favorite is rubbing alcohol since it dries by itself within seconds and leaves no residue behind. On that note, do NOT use anything like windex or other household spray cleaners that leave a residue behind or oily substance, that defeats the purpose and will cause your decal/sticker not to adhere to the best of it capabilities.
After you have cleaned your car, you now need to decide where you want to center your decal in the area you cleaned. I use a measuring tape to measure from different spots on the car to make sure I have it exactly where I want it and that it will not turn out crooked. When I measure I use a piece of masking tape to mark the measurements, normally four for left/right/top/bottom. Then I have a some what boxed area to force me to place the decal where it should go.
Be aware after you stick it, you might can not undo it and use it again, since it can separate the design or text from each other.
After you decide where you want it, go ahead and start to peel your decal back, if it doesn't stick to the transfer tape the first pull, replace the transfer tape and push it together with your fingers or use a credit card to press together.
So you cleaned your area and also decided how and where you are going to place your new decal or sticker and you made sure your decal can peel apart easily.
Now fully peel the decal off the backing and hold it on the tips of the masking/transfer tape. Try not to touch the back of the decal itself since it could leave dirt on your decals back side.
You should have each hand holding the furthest corners from each other and keep it tight so that the decal does not fold in on itself. Place one end of the decal down and then smooth it out to the other end till the decal is fully placed.
Do not fully remove the backing on your decal. You will want to remove about 1/3 of the backing and start by applying that 1/3 of the decal to the car. Then slowly pull more of the backing off while at the same time apply the decal to the car until you have fully installed the decal. Either work left to right or right to left, which ever you feel best doing.
Don't forget you can always buy a $1 spray bottle at your dollar store, put ONE small drop of soap in it and fill with water and shake. Then LIGHTLY (I MEAN LIGHTLY) spray the area and then apply the decal. This is only suggest for bigger decals or decals that you need to be in a precise area.
Waiting... yes this is the hardest part, because most people are so impatient that they can't wait and they mess up the decal by removing the transfer tape too early!
The best way to allow your decal to dry is out in the sun, having it in the shade or in a cool place will only make it take longer. If you used a mist of soapy water when installing your decal and do not let the sun dry it, then it will take a very long time before it adheres correctly, since nothing is there to remove the water and dry the decal to the surface.
Do not try and rush this buy using a heat gun, you can melt the transfer tape and vinyl and when you peel it, it could cause the decal to stretch with the transfer tape. Again the best way is the sun.
Finally just give the decal 30 minutes before you remove the transfer tape, go inside and eat lunch. By the time your done you should be able to go back outside and finish your decal and be in a good mood from that great lunch and nice cold sweet tea! If your decal is still not sticking, make sure you got it in the sun and it is warm out side, and just give it a bit longer.