Handling and Taming Basics for Nervous Reptiles

Handling is the area where keeper expectations and animal welfare most often pull in different directions. Reptiles and amphibians do not seek out contact the way a dog does, and what keepers call taming is more accurately habituation: the animal learning that a large approaching shape is not going to hurt it. Some species tolerate handling well and appear untroubled by it. Others never do, and for those the correct answer is to enjoy watching rather than holding. Deciding which category your animal falls into, honestly, is the first step.
Start with a settling period and do not rush it. A newly arrived animal should be left largely alone for one to two weeks, with food offered and maintenance done quietly, before any handling begins. During this time the animal is learning that the enclosure is safe, and repeatedly removing it undermines exactly that. Feeding reliably is the usual signal that an animal has settled enough to begin. Handling before that point often produces refusal to feed, which sets everything back further.
Early sessions should be short and undemanding. A minute or two is plenty at first, extended gradually over weeks as the animal shows it is comfortable. Approach from the side rather than from directly above, because an overhead reach mimics a bird of prey and triggers a defensive response in many species. Support the whole body rather than gripping, let the animal move through your hands rather than restraining it, and stay low over a soft surface so a sudden jump or drop does not cause injury. Never pick a reptile up by the tail, and be aware that many geckos and some lizards can drop their tail when frightened.
Learn the body language for your species, since the signals differ. Common defensive signals include hissing, puffing the body, flattening, gaping, tail rattling or whipping, and rapid attempts to retreat. Freezing completely still is often stress rather than calm. Several arboreal geckos jump when alarmed. A snake that pulls into a tight coil or forms an S shaped neck posture is uncomfortable. When you see these, end the session calmly and return the animal to its enclosure rather than pushing on, because persisting teaches the animal that its signals do not work and that handling is something to escape from.
Timing avoids a lot of unnecessary stress. Do not handle an animal that is in shed, since vision is impaired and the animal is more defensive. Do not handle immediately after feeding, because it can cause regurgitation in snakes and general distress in others, and leave a suitable gap based on the species and meal size. Avoid handling a newly arrived, unwell, or gravid animal. Wash your hands before and after every session, both for the animal's benefit and because reptiles and amphibians can carry salmonella.
Some animals should be handled only when necessary. Most amphibians fall in this category, because their permeable skin absorbs oils, salts, and residues from human hands, and handling should be limited to essential moves using clean wet hands or gloves. Fast, nervous, and very small species are generally better left to be observed. For these animals, enrichment and interaction can come through target training for feeding, rearranging decor occasionally, and simply providing a habitat rich enough that the animal is visible and active. If an animal that previously handled well becomes suddenly defensive or reluctant, treat that as a possible sign of illness or discomfort and consider a check with a reptile experienced veterinarian rather than a handling problem to be worked through.