Which is a safe coin to invest in the long term?
How long should I hold it?
Is there a risk that I might lose it all?
I am a noob in cryptocurrencies. Help.

I was thinking Litecoin, is it a good idea?
first of all you have to do is never make a decision from someone else, you can do research on these coins. I highly recommend some coins that are in the order of the top ten in coinmarketcap.com. that way you will get some knowledge from the research you do, the decision to invest is very susceptible to what you will get later. whether you will get is a profit or even suffered a loss.