Before you consider speedrunning, you want to be quite familiar with the game, its mechanics and the mission layouts. It's not recommended to start after only one playthrough which can turn off so many people. Especially when it comes to specific movement like the Horse Jump. The excessive resets can be one big issue for most players, in which can be difficult to play with time pressure on them.
One suggestion that might help you getting used to speedruns more quickly: Do not aim for the perfect route and ranks until you reach the breaking barrier. Make back up strats. You should also be familiar with yourself on DMC Terminologies 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 DMC1 Speedrunning.
Refer to DMC1 main page for general tricks being used along with tutorials here: