If you are 18. Less than $150 dollars. First time offense. Shoplifting.
If you're in the USA, or a country similar to the USA, it'll probably make life hard for you forever. Read my other response about a person who stole something 24 years ago:
You can try to get your criminal record expunged, that will help a lot. If you can't, you'll always be doomed to having problems getting jobs and housing, since the government will fail your standard background checks for employment and apartment rental.
Many people have left the USA for this reason, it's a big world, and despite what you may have been taught in school, The USA is not better than the rest of the world as far as living conditions go. Canada is very nice, Brazil, Costa Rica, some parts of Mexico, and most of Europe and east Asia are excellent places to start a new life.
Try to get it expunged first, but I think you'll enjoy traveling, so do that too if you can. Good luck.
do they send teens to jail for petty theft?
or just community service?
or just fines?