Most large ICO is at the moment carried out on the Ethereum platform and, respectively, raise funds in ETH, therefore, first of all, you shall acquire air. It is possible to make it having converted through the exchange other cryptocurrencies in ETH then to send your cryptocurrencies to any off-the-air purse supporting ERC20 standard tokens.
Can serve as examples of such purses: Monee, Exodus, and Parity.
Further, right after the beginning of ICO on the website of the project selected by you the ETH address by means of which collection will be carried out will be published. All you need to do is – to transfer the desired amount on it then according to smart contact conditions you receive on the purse with the support of ERC20 tokens.
You can store the received tokens for yourself or transfer to other users and also bring them on the exchange for the subsequent trade.
In the latter case, it is important to be defined in advance at what exchange you plan to trade as some tokens are provided only at certain exchanges, and tokens of some projects can be used only in these projects at all. Everything depends on their mission, therefore, it is so important to examine conditions of ICO and tasks which are set for themselves by his creators in advance.