of cousre if your not a day trader store your coin at wallet bacause in some reason some exchanger get your coin and said that your account was hack but i dont have a proof that some exchanger do that. Its better than safe than sorry.

It depend on you:
-If you can keep yours private key safe then holding coins at wallet would be a great idea. But you have to do wallet update, sync, convert... yourself
- If you not sure about those things, then chose a big exchange and holding coins there!

 I think wallet is more convenient and secure as compared to exchange, wallet gives you access to your coins at anytime, ant the ability to control and monitor the proceedings of your investment

  The whole question is, what do you need coins for?
I, for example, tried to translate coins on a purse and then for sale back to the exchange, but now I keep on stock exchanges
and only coins that I will not sell for two years or more are on purses.

Trade deposit only on the exchange so as not to overpay for commissions and save time.
The most important thing is to choose reliable exchange with a good reputation.

Keeping a crypto currency on the exchange is much more convenient - You do not need to create a separate wallet for each type cryptocurrency.. Many people consider this method risky. But as for me hacking exchanges - single occurrences. The main thing is to choose a good exchange, and use all the functions of security. 

 wallets offer more security to your cryptocurrency and the ability to control what happens to them. something that exchange doesn't do very well, i believe security of our investments should be given top priority therefore wallet is preferable,

These both things are the ways in order to obtain a huge amount of income but it will be more convenient if you do these things both.
Having a wallet will increase the value even though you do not do nothing from it. Another in exchange you can obtain a easy money in just short period of time and it really gives a huge income.

I think it depends on what you are doing.
if you are a trader, surely better keep in exchange because you will use it more as trading material. but if you are targeting for a long time. you better put in the wallet because it is more secure.

If you have lots of fund in cryptocurrency and intend to hold for long, I'd suggest you keep them in your wallet.
Otherwise, you can keep them in some reliable exchange.