SGNPU25: Well, what has worked for me so far is that I started off with the founder maxing the cooking, gourmet cooking and gardening skill. This is pretty logical since you need to lvl cooking and gourmet cooking to lvl 10 for ambrosia. I made her traits creative, genius and something else (forgot the last one) and her aspirations were master chef and botanicus thing. Sorry if I don't translate everything correctly. I have my sims in another language than English. I gave here the cooking career as well.
What I noticed is that at the moment you are in an inspired mood and start making meals, your cooking levels incredibly fast. (that's why I picked the creative trait). Also the focused mood is good for gardening and things like fishing etc. From day one I bought seeds for my garden and planted like 12 of them, so that she had to take care of her garden every day and level her gardening skills. She needed to get to lvl 7 anyway to be able to make a death flower plant. I got her switching between the two aspirations (depending on what she was doing) and this made those go pretty quickly as well. Another important thing is to start moving other sims in at a later age. At least that makes it easier in my opinion. I had her meet someone and let them live together when she had become an adult. So all the time before that she could focus on all her tasks. Also I did wait a while before getting her pregnant, since it makes it harder too.
Also I made the sleeping potion a thing all the sims can use, so not a unique requirement. I made fish the museum pieces since she needed to fish as well for angelfish (again for the ambrosia).
She had a lot of nights that she stayed up to work on things and this makes it much more doable in my opinion.
With the second generation, I had the child complete the Whiz kid aspiration and I believe this gives you the fast reader trait? and I made him also a genius and a nerd or something. Because of the aspirations is choose (also something like whizz kid and angler) he got the quick learner trait too. So he levels quite faster than normal sims. His 3 max skills are handiness, fishing and the one you get from playing chess end such (can't think of the name right now). So made him all about skills he could level with the focused mood. Also I gave him the unique reward of reading books faster, so he could level quicker. Used the sleeping potions on him as well. I gave him the astronaut career and at a later point you unlock a drink at the bar that gives you energy too (not full, but quite a lot) and this is handy for later generations as well.
I start with the aspirations and the levelling, get a spouse at adult stage and start with birthday party (since you they age up anyway and the gold medal for date (when they are already together, so you can both tell them what to do) and the wedding one (I do that at their own house and make sure everything is there). Then it just leaves me with two other parties and those are done pretty easy. I always make sure that every household member is home at parties since that makes the tasks 10 times easier. I made the museum pieces of the second generation pickings from the garden.
Now that the founder is done with the requirements and the second generation as well. I just let them take care of the ambrosia requirements. Make them fish, take care of the garden and complete as much whims and other things to give them those points to buy life positions. I have a storage room on my lot where I keep all the ingredients.
I'm not sure how I'm going to do the third generation yet, still thinking about it. I hope this gives you some useful information. I didn't plan it ahead that much to be honest.