The slider may look light for it's size but never under-estimate the weight of an adult slider.
For young red-eared slider, it is pretty light-weighted. You can carry it by placing your thumb and index finger at the edge of it's carapace (shell) and lift it onto your open palm. Remember to keep your grip firmly (but not squeezing too hard) on it's shell so that it won't crawl and fell off you hand. When placing it onto a surface, do not just dump or throw it, put it down gently. The turtle have to feel secure, so prevent shocking them.
The bigger slider have to feel heavy for it's size, it mustn't feel "hollow". To carry it, use both your hands to grip both sides of the shell firmly and in a position you are comfortable in before ligting it higher. You might have to use a little more strength as the turtle that dislike to be carried can do much struggling. It will flip it's legs and try to struggle out of your hand. Beware of the claws, they may be quite sharp and long and they scratch. I advise young kids to avoid handling adult sliders, for they might drop the slider and injure it.
DO NOT carry a turtle by it's limbs, neck or tail. Always carry it by it's shell. ONLY a Snap turtle can be carried by it's tail because... it might feed on your fingers! Anyway you wouldn't want a Snap turtle as pet, it is too dangerous.
Pet red-eared sliders usually won't bite. But I don't know if wild sliders will bite. Babies sliders will sometimes mistook your fingers for food, but their bites are only nibbles. You can sort of anticipate when the turtle will bite... they will be focusing on that object cross-eyed! DO NOT attempt to make a turtle come out of it's shell when it doesn't want to, they might make a sudden bite attack on you.
DO NOT keep turning the turtle on it's back when playing with it, they wouldn't like it. Small turtles can flip themselves over easily, but larger turtles will have difficulties because of their weight. On hard surface, they may scratch their shell in attempt to flip over.
Remember to wash your hand before and after handling!
Do not play with your pet turtle to much and carry it about for too long. It might die of "too much love", to be exact it might die of stress.