This is the easiest way.

• Use a centralized exchange (like Kraken, Binance…)
• Buy LTC, BCH, anything you want
• withdraw that
• Swap (exchange) those through a swap service, from the crypto you bought, to XMR.
  • https://trocador.app/ is an exchange aggregator that’s privacy friendly and Monero friendly if you want. They don’t take any cut and you can get better margins this way.
• Optional but I recommend it: churn your crypto by sending all of it to yourself multiple times, waiting a few days between each churn. Easier to do with Feather Wallet on desktop as it has coin control. This minimizes the links to your identity: Monero shines through multiple transactions, but tx to tx can statistically be liked. The more you do, the blurrier it gets.
  • On Feather Wallet (which is open source), there’s a “coins” tab where you can see each unit of crypto you have, and can “sweep output” to “yourself (churn)” easily.
• Spend your XMR, have fun :)