There are a few options for you to start investing in crypto:
+ Create an account on an exchange, perform KYC and buy coins/tokens with a bank card;
+ Use a number of platforms that allow you to buy crypto easily with your bank card;
+ Buy crypto from a friend or relative;
+ Appear at events, carry a large board with your wallet QR code and the words "Please donate BTC to me" like a boy did many years ago. Just for laugh

I don't know how much $ you have, as this determines which coin/token you can invest in. Spending $100 to buy BTC at this time is not a good suggestion because profitability is not high. If you don't have a lot of money, you can invest in some cheap, potential and noticed tokens recently.
ICO/IEO are always good suggestion, but make sure you have the time and ability to find a good project.