If you take a spell as a Sorcerer you'll always use your charisma to cast it. So if you have a low charisma and are tking the Sorcerer levels to get the meta magic abilities, you should choose utility spells and spells that do not have attack rolls or DC checks.
You get spells automatically with Druid and Cleric so you'll alway use your Wisdom as the casting stat. No sense in also learning those spells as a Wizard.
You should decide which class will be the one to cast your attack and control spells and try and only take your attack spells with that class.
Also the last casting class you take your first level with will determine the casting stat for your scolls and items. So if you have +1 Cha, +2 Int and +3 Wis it looks like Druid is your main caster and you should take Sorcerer at level on for the Con save, then take Wizard and take Druid last so that you use you high Wisdom for scrolls and items. Then you can take any combination of levels after that.
