I’m in the same situation and will say how I went about it, though thats not saying I think it’s the right way.
When I first bought SF4 and it was all shiny and new, the first important thing I wanted to sort out is character choice - I had intended to main Guile as he’s my favourite alltime SF character, however I play on Keyboard and for some reason (despite being a charge character) it was extremely awkward to pull off some of his moves, even sonic booms for some reason. Once I messed around with him and realised this, I looked at Balrog (Always enjoyed watching the character being used in Tourny videos) and gave him a go - Strangely enough, despite most of the motions being the same, his moves flowed so much easier and by the time I had done his Normal Trials, I was hooked.
From there I hit HARD Trials to learn more and it took quite a while but I eventually got them, despite having no knowledge of links/cancels or any of the fancy details that makes combo’s easier - Once I got it I was so proud and headed to Champ Mode to take it to the onliners (I don’t recommend doing this, by the way, ESPECIALLY if you’re on GFWL which has the utmost lowest skillcap of all SF4 ports).
After a month or so of random headbutting around like an idiot I got invited to Player Matches against fellow Irish Players (Most of which are used to offline games & tourny events) and I got my ass rightly handed to me over and over again.
At that stage I knew it wasn’t all good, so thats when I first encountered SRK and hunted down Matchup Information about each character - Ironically, at this point, I still couldn’t even perform a JabShortHeadbutt (or any BnB combo for that matter) and I decided to work on them both, hitting the training room to practice my combo ability inbetween reading up all the information I could from SRK as well as watching more professional matches on SFDojo website to help with matchup experience.
Time went on very very slowly and after each session I would highlight something I knew was wrong with my game and use the limited time I had to better and improve on it until I was happy, before picking something else. I find that a big mistake people make with SF4 is assuming everything is easy to learn and try to tunnelvision everything in one go, it really doesn’t work that way, especially considering the vast variations of styles required in matchups vs certain characters, meaning almost each one has it’s own learning curve.
As of right now I’m immensely proud of my average’ness, moreso as I’m a rare Keyboarder, and I can pick apart my bad habits one at a time and work on them with each SF4 session.
I literally started from scratch. Until recently I couldn’t even use focus attacks, cancel moves, had no knowledge of what was a linkable move or what combos required said links, had no footsies, no mindgames, no spacing, crap at punishing, no mixups and barely ever used Balrogs awesome normals at all. The last thing I need to work on are option selects so thats my target at the moment seeing as I can perform a wide range of combos, have ok execution and have my own style mixed with a decent understanding of most matchups. Once I get option selects in my book it’ll then be about polishing everything off - I wager I’ll be ok by the time SSF4 comes out but in fairness, they probably wont release that on the PC so by then I may have to quit which is a shame but at least I can say I gave at least one SF4 character a thorough going over and really enjoyed my learning process and can step into (most) games and put up a half decent fight.
*Start off simple, one (maybe two things at a time) and build from Trials (They teach you platforms to all manner of combos, so you’d do well to know most/all of them off by heart)
*Once you get them, hit that training room and experiment with mixing them up and varying their possibilities, all the while polishing off your execution and ensuring you can perform most (if not ALL) essential BnB combos.
*Get to know all opposing characters - It’s one thing being great with Balrog but if you don’t know a matchup, you will not survive. SRK alone has a lot of information to help with this and for visual reference, be sure to watch high-end SF4 games to see it in motion.
*Hit the gory details, focus attacks, cancels, when should you FA, when should you cancel, how to use them aggressively/defensively and, in other words, how to manage your Super/Meter bar effectively and not waste anything needlessly.
*I’ve met players who dismantled me with extreme prejudice using nothing but normals, you have to understand their power and ability - It’s all well and fine throwing out a sea load of special moves but sometimes all you really need is a tap of a punch/kick button - Get to know the moves and their uses.
*Once you have a basic grasp and are solid with the regular everyday Boxer stuff, hit the nitty gritty side of things one at a time and just polish everything you’ve learned.
It helps to get as much experience as you can beit offline or even just online Player Matches against people you KNOW can teach you something. Mistake I made was assuming that beating up jumpback spamming projectile loving shotos in Champ Mode taught me something - It doesn’t, so leave that stuff as a break away from the learning process, not as an actual place of learning. The only good thing Champ Mode does for you is put you in a spot where you have to adapt on the fly, and this can be difficult depending on how you play.
I’m nothing fancy but enough to give the average Joe a hard time - Example, Bloke I’m playing is a Bison player who 6:10 times beats me comfortable and I didn’t expect him to swap to Guile for a match one day and considering it was best of 5 that gives you plenty of time to try and suss a player out (Another important but un-Rog related factor).
They recently changed the tier list to make Rog/Guile 6:4 in Rog’s favour for arguably good reason, and there where a few bits and pieces I made myself aware of to make the match easier.
Tested him out to try and adapt, Jumping in to see if he’s quick on Flash Kick, keeping out of FK range and trying to bait them with FA’s or standing jabs, even tried a meaty (didn’t work, but it still hit) overhead on wakeup which isn’t a viable approach at times but if it works then knowing you can’t hit a crouching Guile with a Short after the Overhead helps (example of matchup differences) so you need to know what you CAN use (Crouching medium punch / strong) and thats another thing to test in the training room - Some basic combos just don’t work on certain characters, so you need to know what other options you can use in their place. Also knew he had no wakeup answer for Rog when chippable vs a timed EX HB, not even Ultra.
Anyhow, rant over - Take it one piece at a time, don’t try to overload yourself with huge lists of things you need to work on - It’s also a plus if you can record games so that you and other people can review them and point out the good/bad.
In other words, what Leoncio said: “Train smarter, not harder.”
Hope it helps and best of luck with your experience!
Edited out one of my movies - it has no place in this discussion, really.