How or where is best for you to store you cryptos?

First, what are your plans for your cryptos?
Do you want to trade them regularly? Do you want to hold on to them for a very long time?
Do you plan on transferring them to other people or locations frequently?

Don't forget to check out my "Additional Reading" links at the bottom of this post to learn more about mobile wallet security issues and Dmitry Buterin's top 3 crypto wallets.

If you plan on trading coins regularly, it makes more sense for you to store the coins you want to trade frequently on the online exchange that supports that coin.

Exchanges are the easiest way to store your cryptos, but it is by far the least secure. In order to help counteract this vulnerability, the very least you can do is use a very secure password along with two factor authentication.
I suggest using a password generator that includes upper and lowercase letters and numbers that is 16 characters long.
You can download the free Google authenticator app and link this to any exchange you use.

If you are looking to store your crypto for the long term, and you don’t have an interest in trading or transferring them, then I’d suggest looking into what is called “cold storage” wallets.

These come in the form of paper wallets and hardware wallets.

Cold storage refers to the fact that your coins will be taken offline.

These cold storage wallets will give you peace of mind knowing that there is no way for a hacker to access your coins- that is until you decide to bring them back online to either sell or to transfer to a different location.
Cold storage is very secure, however they are not the most convenient.
Paper wallets can be produced using
bitaddress.org for bitcoin, or you can use walletgenerator.net for other crypto coins.
You can also purchase hardware wallets which are relatively easy to setup and are more convenient for making transactions with your coins than a paper wallet.

There are a couple of things you need to remember when setting up and using a cold storage option.

If you are using a paper wallet, upon setup, remember to disable your wifi or internet connection when the address is being produced.
Also, never keep any coins in a wallet that you have exposed the private key.
If you want to withdraw any crypto out of your paper wallet, I highly suggest that you take everything out of the wallet and if you have any remaining coins you wish to keep in cold storage, make a new paper wallet for them. I’ll include links down in the description to tell you how to produce paper wallets and withdraw from them.

If these first options don’t suit your fancy, no worries! the options abound…
So you can always download the official wallet of the coin onto your computer, for example, you can download the bitcoin core wallet, or the ethereum wallet, the ripple wallet, the dash wallet, the zcash wallet, and on and on, the list continues for all other crypto coins as well.

These official wallets are all different with different pros and cons and capabilities. These wallets are far more secure than holding your coins on an exchange, these wallets also make tranferring these coins easier than using cold storage.

One major benefit for using official wallets, particularly the ethereum wallet, is the fact that many ICO’s utilize ethereum and in fact require you to invest ether by only using an official ethereum or mist wallet.

You can and absolutely should backup these wallets by saving your .dat file on a USB drive in case your computer is lost or damaged.

But, these wallets do take up space on your computer, and they might be confusing and are almost always time consuming to set up, however I highly reccomend using these wallets if you don’t want to worry about the lack of security on exchanges, or the hassle of transferring them in and out of cold storage.

Additional Reading/Sources:

Paper wallet Tutorial
More on Official wallets
Q&A Best Crypto Wallets- Dmitry Buterin lists his top 3 picks
Mcafee explains the lack of security for mobile crypto wallets
List of all BTC wallets
Trezor
Ledger
Keepkey