Struggling to parse the regional differences between Huasteca and Central Nahuatl

I've been using a mix of online dictionaries and YouTube channels, but I've realized some sources use 't' where others use 'tl,' or have completely different verb conjugations. I want to focus on one variant to avoid confusion, but I'm not sure which is more 'standard' or widely documented for a self-learner. Should I stick to the Classical-based orthography used in Central Mexico, or is there a better entry point for a beginner?