A lot depends on the additude of the leo, and the amount of time you're willing to work on it becoming comfortable with you.
You shouldn't be afraid of it's tail falling off, unless there is good reason. The tail is a MAJOR fat reserve, and the gecko will want to hold onto it, unless it thinks it's in mortal danger. A really big scare can sometimes do it, but usually some sort of trauma needs to occur (like pinching or grabbing).
Always try to scoop your gecko from below, around the belly. Don't grab at it if it tries to run away. It's too easy to miss and grab the tail on accident.
I work with my gecko for at least a minute a day because it helps them to become familiar with you. You can handle them for up to ten minutes a day with few problems. They will become stressed if handled too much. You should immediatly put the gecko back if it start looking stressed/anxious.
Handling consists of allowing it to walk freely along your arms and hands. Many geckos will snuggle next to your neck (one of the warmer points of the body). When starting out, you may want to do this over a soft surface like a bed. Young geckos are pretty well known for leaping off for little reason.
They don't appreciate petting at all. You might be able to work with it to the point that it does not mind, but for the most part it feels like something poking or attacking them and it can make them panic.