Well, Professor, the fact is I didn't all that much. In those days I was just a dumb teenager scared to screw too much with the program. I first thought this post would instead deal with how I'd houserule 3.x to make it into something I'd willingly play, but the muse is a funny and fickle creature, so instead you're getting a little piece of the d20 (And 4e, and pathfinder, and surprisingly even 5e-- I'm nothing if not promiscuous with my blasphemy!) generation brought back to the OSR-- and my latest awful modern heresy.Ooh, I know! I love reading other people's house rules (despite it being a cause of so much frustration), so maybe a list of some you've used in the past. I'd be especially interested to know how you modded 3E "back in the day"
Here's some skill rules I'd like to use in the future:
Every character begins with a number of trained skills equal to the number of skillpoints the corresponding 3.5 class receives per level or 4, whichever is higher, plus their Intelligence modifier. Humans are trained in one additional skill. They may choose from the skills available to their class in Pathfinder (which streamlines things somewhat and removes from its skill list the horrible evil that is Concentration), except for Craft and Profession, which are covered by the normal Secondary Skills chart (the one in the LL Advanced Edition Companion, for example). An untrained character may attempt to use a skill by rolling 1d20+the relevant modifier, a trained character adds half their level (rounded up) to the roll.
A character may train in additional skills, languages, secondary skills, weapons, or types of armor not otherwise available to them. To do so, they require 1d6+3 months time studying under a trained teacher, and they must devote at least four hours per day and five days per week to studying. Most teachers will expect a reasonable compensation, on the order of 2d6x10 GP per month. The maximum number of such extra proficiencies they are able to retain can be no more than the amount of skills they started with plus their Intelligence modifier.
All thieves (and other rogues, such as Bards and Assassins) must be either very lucky or very talented to progress in their chosen career. Choose two skills, plus a number of skills equal to your Intelligence modifier. When using those skills, you may roll twice and choose the better value. This is intended to replace the special advantage provided by the percentile thief skills (and Hear Noise), which are otherwise redundant in this system.I think this is an interesting rule, so if you ever want to use skills in your old-school game in the future because you're crazy like me, and you elect not to use the LOTFP ones (which are also pretty nice, even if I think LOTFP itself relies too much on shock value), I hope you'll give this a try.
Edit: And here I am the very next day rethinking this rule... It's not that I'm fickle, you know, I just overthink things. One day I need to write a big post about designing like a Taoist.