IMO it's really a great opportunity to buy some bitcoin before halving.

If you want to buy with only cash:
Buying with cash is not that hard if you know someone who know about crypto currency or related with it. You can find someone who want to sell btc for cash, then negotiate and deal with that person about how much you want to buy. It'll be better if you deal with that person face to face. Otherwise there is plenty of chance to get scam.

If you want buy with credit card:
If you have a credit card it'll be easy to buy it. Cause many p2p exchange will give you opportunity to buy btc with master card or credit card. Because you are a citizen of USA i'll recommend those exchange which is legal in your country. Like Coin base Pro, Binance US, Kraken etc.