Sign up for nostr.wine.

Add the main relay and follow instructions to add the filter relay.

If using Damus, in the global tab, select hamburger in the top right and allow only paid relays.

You can pay directly from a custodial wallet/ramp that supports LN such as cash app.

Other popular paid relays are eden.nostr.land, atlas.nostr.land, puravida.nostr.land.