Penang or GTFO.
Seriously though, a good Thai recipe book on curry or an online source you trust is going to be your bet here, and not subbing out ingredients for the western equivalent.
Elsewhere people have already mentioned avoiding certain shortcuts, but I think you’re going to have to make some allowances the first time around, like a food processor versus using a mortar and pestle. As you track down more ingredients over time, try them out. You might have to go to multiple stores.
Lots of excellent advice in the thread already (could kick myself for not including shrimp paste!) but the truth is there are no surprise ingredients or techniques.