Be quite familiar with the game, its mechanics and the mission layouts. Do not start after only one playthrough which is the most difficult in DMC5. Unless you are playing Vergil since his runs does not require you to learn complex skips like Nero Dante and V. However, much like DMC5 the more you keep playing DMC5, the more you will stick around for a long journey This run starts out as a long run for beginners and excessive resets is one big hurdle from big progress unless the currency route is not within your favour. This is common in Human difficulty where the route is much tighter and harder. It's advised to refer into different perspectives over what to do and whatnot. Do not focus too on one runner. Make your own theory-crafting strategies and get familiar with the Terminologies and safe methods that are used during the runs. In the following sections, you will find important concepts and information that you may find useful for starting out with DMC5 Speedrunning.
Refer to DMC5 main page for general tricks being used along with tutorials here: