Having some major difficulties completing some characters' normal combo trials

I wasn’t sure if posting here would benefit me very much, as for one thing I was thinking it’s not very likely this forum is all that active as I’m sure SSFIV is much more frequently played by most people who would frequent these boards, though this does pertain to SF IV so I thought it’d be more appropriate to post this here as opposed to the SSFIV boards.

I was also thinking my request for help here might be met with some derision, as I’m sure most people who post here are at least semi-pro level players, and at best I’m just mildly adept hence my request for help with what I’m going to be requesting now.

With all that out of the way, I’m having some major difficulties completing some of the normal trials with a few characters, pretty much exclusively charge characters (Boxer, Claw, and Blanka, and Gen is the one exception as far as fluid motion characters go, though I have an arcade stick I’ve gotten more accustomed with and so I think I’ll be able to compete his trials with that, as I haven’t tried that yet).

I have completed all of Bison’s trials, so apparently I am capable of performing moves fast enough, though a lot of the time when I need to get a charge move to combo it simply won’t come out fast enough, or my move won’t come out at all despite the fact that as best I can tell I’m performing the correct input. I’m not sure if I’m simply not pressing the 6 direction fast enough to get the move to combo, though I guess that’s possible, though I guess if there’s a means to combo those moves faster than what I’m aware of I guess I’m receptive to learning that much. I’m also not clear on how one is meant to super cancel with most charge characters, as I know that’s been required within some of the trials I’ve gotten stuck on. Apparently despite being charge characters, in order to super cancel with them one doesn’t need to actually charge their supers whenever the conditions are specified within the trials that require the cancel, so essentially a player just presses 646 (corresponding attack button) beyond the point the move that the super needs to be cancelled from occurs?

As I already referenced, I’m not sure if this question will receive any attention, and it’s possible the attention may be negative if it does, though if anyone can clear up some of the discrepancies I’ve been faced with and/or just give some general positive suggestions that’d be appreciated on my end. Thanks in advance.