Approach handling a rat similarly to to how you would approach handling a cat. If the rat doesn’t know you, don’t expect it to be 100% comfortable with you picking it up (of course there are some exceptions to this – some rats just love everyone). If your fingers are tense and you squeeze it, expect it to try to wiggle away. If you are nervous and jumpy, expect the rat to be nervous and jumpy too.
With new rats, the best thing to do after they’ve come to live with you is spend some time with your hands in their cage, letting them sniff you, climb on your arms, and get used to you being around. Try gently scooping them up with two hands and letting them jump off. This will teach them that being picked up doesn’t lead to anything they don’t like. Once they are happy to come up to you every time you open their cage, try using your hand scoop to get them out and let them run round on a raised surface while you sit with them (couches work well for this). Wear something cozy that they can scramble around in, or lay a blanket over your knee that they can crawl under.
Once you have befriend a rat it will usually be excited for you to pick it up for snuggles. One way to do this is to wrap one hand round its middle just behind its shoulders, with your fingers meeting underneath, and slide your other hand under its back legs. Alternatively, the scoop method, where you scoop the rat into two cupped hands, is great for rats that aren’t likely to want to jump away. Rats should never be picked up by the tail as this can cause the skin of the tail to tear off the bone. This is called ‘degloving’ and most often happens at the tip of the tail when it’s pulled with force. If you must, you can hold a rat by the base of its tail as long as its body is supported and its not dangling.