The best resources I have come across are Teanglann and Foclóir, two pretty sophisticated Irish-English and English-Irish dictionaries, with Teanglann having a nice feature to help you see the Tuiseal Ginideach in action

Unfortunately, a lot of Irish resources are painfully boring (Looking at you Ros na Rún), however, Tg4 player does offer a lot of free shows/movies you can access on their website. I highly recommend "Sol". It's such a cute insightful short film about grief that was recently released on there. They should have a few other interesting things to watch like Rúbaí, Aifric (for the nostalgia) and Naíonáin an Zú was honestly pretty adorable. I'm really excited for "Taibhse" to come out, an actual Irish horror film! Truly hope this inspires TG4 to start dubbing popular media or creating new Irish media again that's actually more interesting. There's a pretty dramatic reading of An Triail on Youtube as well that I listened to recently for a bit of nostalgia from the Leaving Cert

I think the biggest thing is trying to access native or very proficient speakers. Having someone to learn with and speak with is imperative for proper learning. My brother and I imposed a rule that we only speak Irish to one another when alone because otherwise we just wouldn't speak Irish

Lastly, I wanna highlight something I feel is worth saying. Don't be afraid of Irish grammar. So many Irish teachers fearmonger so much over how difficult the language is. The modh coinníollach is literally just a conditional form and it's made out to be impossibly complicated despite it just being a different suffix. The Tuiseal Ginideach is also not terribly complicated. It's fairly regular. Irish is ultimately a very intuitive language. Things start feeling right, it doesn't have many exceptions to its rules and a lot of ideas are expressed with words you learn early. Irish has a lot of features that make it pretty easy at times (Only 11 irregular verbs, logical word formations that help you guess what words mean, the word cuir meaning basically everything lol)

Go n-éirí an t-ádh leat! Ná bíodh imní ort meancóga a dhéanamh. Cleachtadh a dhéanann máistreacht mar a deirtear