Please note: the steps below have been used on cotton clothing, I have not tried this on synthetics.
First, and the MOST important step to removing latex or acrylic paint from clothing is to immediately put the item in cold water, ice cubes work too. The sooner you can get the item into cold water the better. However, I have done this procedure with clothing that has sat for a day or two and while the results aren't as good, it does still work. Do not use hot or warm water, or put the item in the dryer or use an iron on it until the stain is removed. Using any sort of heat on the paint stain will cause it to set and once that happens, the paint will not budge!
You can also add some dish soap to the stain and work it in a bit before putting the clothing into the water. Let the item sit in the cold water for a while. I usually let it sit for a few hours. Depending on the size of the stain and how soon you get into the cold water, will determine how quickly the paint will start to dissipate without having to do much else.
Next, grab the dish soap, any old dish soap will do, and apply the dish soap to the paint stain. Rub the stained fabric together. Rinse (with cold water), and repeat until the stain is gone. Once the stain has been removed, you can launder and dry the item as usual.