A quick question?!

is it better to invest a lot in one coin such as bitcoin for example. or invest a little in lots of different coins?

I think there is more chance to earn if you invest in few different coins GL

Well everything I have learnt in my finance courses is diversify, so I think you should stick to that. Invest in multiple coins, however, this doesnt mean throw you money at coins. One thing you will see in the Crypto space is "signal groups". These groups focus on daily tips, which is impossible to win. The best rule in my opinion for investment is limit your trades. Meaning only buy and sell 4-6 times a month, total. These trades should be something you are sure about, and not just a quick educational guess.

Like others have said, focus on smaller cap coins. Don't be fooled, some very solid projects are also yet to moon with valuations which are still "low" (read in single/double digits, not less than £1/$1). Most importantly, only risk what you can afford to lose. Smaller coins can go up very suddenly, but in the same avenue can also drop very quickly. Best of luck.

Bitcoin is your safest bet but you can invest on other coins that are established like litecoin, ethereum, Dash, Monero, Zcash