I wouldn't panic about immortals accidentally maxing Cooking from occasionally cooking a meal instead of eating leftovers - I just finished supermaxing the skill for my current heir, mostly through cooking meals rather than studying the skill books. I think he hit level 10 in the skill somewhere around 60 meals, and I'd be astonished if any sim autonomously cooked that much. Charisma, though - if you leave it as a supermax (which I really, really wouldn't recommend), nobody else can ever get so much as a single point in it, because every social interaction they ever do, down to snuggling the nooboos, will increase the skill.
If you plan to have Handiness as a supermax, do it early, so that Handy Sim is there to make repairs and upgrade stuff...
One more thought: At the beginning of the game, check the consignment store frequently. Buying uncut gems worth more than about 40 simoleons and unsmelted metals worth more than about 60 simoleons will bring in some cash, and cameras will turn up from time to time. Even a photograph taken by someone with no skill using the cheapest camera can be hung on the wall for your founder's YA photo, and then you've got the whole game to let it appreciate.