Go through different ICO reviewing sites and find suitable one with good rating.Purchase some Ethereum because most of the new project only accepts ETH. Now send those ETH to contract address of that token (be sure to only send ETH to official contract address).Don't send ETH from exchanger wallet, you should send ETH from ETH address created with myetherwallet so that you can view tokens you will receive after sending those ETH to contract address of the project.After you will get tokens, now you have to add custom token in your Myetherwallet dashboard using parameters given by the project.After this you will see your tokens and you can send those tokens/coins to any of the eth address you like. To exchanger's deposit address after some exchange platform will list tokens you have bought.As simple as this.