Chapter 1. Montressor

• the invincibility glitch is made by exiting to hub just as you lose your last life. So simply jump into the void and as you fall, pause -> hub out
• I found out recently that you don't need to slash when you use the infinite fall glitch, just jump and direct yourself to the point, it is more consistent and easy
• in the bird minigame be sure to hit the last birds before screen switch ASAP. They are the most important.
• the last area loads somewhat quirky, so walk a little bit further on the right before the bridge to load everything
• when climbing ladders you need to jump just before you reach the end thus skipping the animation of Jim pulling up

Chapter 2. Spaceport

• you can jump straight to the first map crate in the beginning. Saves some time
• you can jump on the ledge without moving the crate at all before the elevator, it is frame perfect tho
• be sure to have 200 gold to go through the last gates ( you need to collect 50 gold in two levels, but don't go off the route to get them, just collect some on the way)

Chapter 3. Scroop

• if you hit him while he pulls the switch, you will skip his jumps to the centre, it is easily on the first bomb and barely doable on the second one, just be sure not to pick up the bomb immediately, wait a bit
• in the second phase, practice to hit the thing asa you pick up the bomb
• on his last health, you can hit him in the air, saving some time

Chapter 4. Silver

• there might be a pattern for the first phase, but I found it to be random, just be quick and pop all the crystals
• in the second phase, the pattern of the mines is the same

Chapter 5. Races

• in the first race you must get 150 as it is the easiest way to gain it before the second level
• you must save quit after crossing the last lap in every race apart from the last one, there you need to wait until the end
• personally I use R2/L2 (fast turn) a lot, helps me a lot during tight turns and especially on the last race

Also you can watch the guide on YT