For the SR categories, you should always type the cheat "speedrun" into the options BEFORE starting a new game, this will activate the cheat without it costing you any time at all. Plan your route accordingly, fighting enemies at much higher levels than you is risky, but can give you a lot of levels at once so it is often worth it. Know where different levels of enemies are so you can choose who to fight best.

Manage your ES!!! ES is the most important stat in the game so make sure you never get KOd and you never heal at any heal stations so as to not reset your ES. This does mean that you will have to buy Cones(TM) of Water in order to heal Jeebo & Blade, but Jerbo can self heal with Laze, so usually you don't need to use them on him (unless you just have a huge excess of money).

For 100%, you need to save money. The Traveler's Journal is required to complete 100%, and it costs 1000 Magnicorns, so make sure you save enough to get it. Not hiring a lawyer is a good way to save money, but keep in mind you will need to be a fairly high level in order to survive without one.

For any%, it may still be beneficial to grab a couple of collectibles early on as they give a large ES boost. Getting 1 or 2 cookies in the Cerato-escape sequence at the start of the game gives you a pretty good advantage starting off, especially since the 1st and 3rd cookies aren't even really out of the way much to get.

During boss battles, it's usually a good idea to spend a turn or two buffing yourself. This will help you kill the bosses faster. Too much buffing wastes time though, so try to balance it out.

That's it for the basics, there are way more ways to speed up your play, but these should get you started pretty well. Thanks for reading, and I hope these help!