I think getting a dynasty done all depends on your mindset when you start one. My mindset fluctuates as I play my game because it likes to throw me curve balls that I'm having fun working with.
For an Immortal Dynasty, you have to think that you need at least level 7 gardening, at least level 5 fishing & the ability to fish with bait, level 7 painting and level 10 cooking. You can have your founder do any of these except the painting. The most important thing regarding a dynasty is actually getting painting first. Not the heir, not the founder's supermax, not the fishing or gardening (although you should start that early on). Painting level 7 for another Sim is the most important thing for a dynasty founder. Whether you bring in a new friend or a new mate, painting level 7 needs to happen first and within 2 weeks. Depending on what town you live in, there are Sims that already have a high painting skill that you can move in to get it out of the way to reduce the stress of that first generation. If they don't have painting skill, I recommend small paintings but that is also personal opinion and debated. Having a founder take on fishing, gardening or cooking is another way to help reduce the stress because your founder is also working on something that has to be done anyway.
I have failed four or five dynasties when I was first trying them because I was unable to get the painting for my founder in time.
As for the DecaDynasty, If you've having problems understanding it, just ask (in the thread of course). It's a wonderful challenge and no one will think differently of you if you can't figure it out. We had to all figure it out too at one point.