I've searched and there seems to be a lot of guides around the place and mostly posted around 3 years ago or so. Are there any updated guides or staple guides that people can recommend?

For SL1 not really, no. Most resources available are on the speedsouls wiki, otherwise your best bet is just watching runs and following along - feel free to join the speedsouls discord for more help as that's where the most people are active.

https://docs.google.com/spreadsheets/d/19GMDO2F7vBZrIQsa79idLOaa0ExokY1BWAo6OaSiQsI/edit#gid=0 ( french guide, English translation is in progress )