Become Proficient in your Armor
It'll cost you two feats, but since you're a Rogue, it should only cost you the one.
Light Armor Proficiency
Arcane Armor Training
Every turn, spend your Swift Action to reduce the spell failure by 10%. This would be great if it didn't require you be CL 3, which you will eventually be, but not realistically soon.
Mithral Armor reduces spell failure by 10%, but it doesn't transfer to newer suits when you want to upgrade. Be prepared to wear the same mithral shirt every day for the rest of your campaign.
Don't Cast Somatic Spells
One thing very few people think of is just avoiding spells that require movement. If you work strictly with verbal spells, there's nothing you need to worry about.
Stop Needing to Move
Still Spell, costs a feat and a spell-level, but makes all of your spells Verbal only. As a Sorc 1, you're never going to be able to benefit from the feat itself, though. Alternatively, you can get a Lesser Rod of Still Spell for your Level 1 spells. Keep it at your waist or in a wrist sheathe for easy access and out the window go your chances of failure.