thank you!! i have some tips to offer you but the most important one is: study and practice. copy HS panels as close as possible and take note of how the characters are drawn, how simplified they are, and try to mentalize the 'patterns' you find within those art styles. then apply what you learned with an entirely original panel.

use the comic's panels as reference as much as you need and eventually it'll come out naturally. if you don't have references for specific things, try to find something that's relatively close to what you're looking for and take aspects from that as reference and wing the rest.

it's also very important to study the character design philosophy if you really want to nail the style. you can be the best at replicating the art style but if the character itself looks like it belongs to an entirely different universe, it will be way harder to make it look legit. you can still try and you may succeed, but it makes the job way easier when everything looks cohesive and works in tandem.
backgrounds are very important too. they may look intimidating to learn but HS panels are very small canvas-wise and they don't have to be (and often aren't) crazy detailed, so that makes them easier to draw.

if you're unsure you nailed the style you could ask for a second opinion on what you could improve, or alternatively put your panel besides one from the comic and see what deviates from the original. i often make the heads too round and i have to look for references from the comic to remind myself to make them wider, stuff like that.

semi sprites are the easiest to learn as they're some sort of middle point between sprites and hero modes, so i recommend looking into learning those first.