The builders guide by LND is pretty good: https://docs.lightning.engineering/

Other than that, it gets even easier if you were to use integrations like LNBits or some of the WebLN stuff that pop open an extension for users to easily pay. I also like what Mash has bee doing to make it easier for content creators to get paid for their work more seemlessly on the readers side. Other than that there's also probably some other integrations I'm missing. But if you're trying to do it yourself, the LND builders guide is a great place to learn.

I think some of the struggles come down to if your app should connect to the users node. If it's your own node, it's a lot easier to deal with, you would just need a backend that connects to your LND node that does something simple like make a payment or get an invoice.