One of my little Sim families has an unemployed gardener who has a massive garden and a penchant for repairing things. She's built a rocket ship in the backyard and just from that is level 5 in rocket science and level 5 in handiness. Actually, she's pretty high in a lot of things, cooking, comedy and I don't even remember all the rest. I didn't particularly pursue anything except having her gather everything she could and garden, so all the other things happened accidentally, like through social actions, (comedy), or needing entertainment, (playing games). She and her spouse always have full social bars because they are always together except when he is at work. She just had her first child so I think rockets are not in her immediate future, although being an astronaut is the only career I actually considered for her.
Her hubby is a chef and had progressed up the ladder rapidly. I'm really not sure why, but he's done pretty much everything to become a master chef without much effort or managing. Ok, I did have him cook, cook, cook, but he never got stuck without getting promoted. It seemed a pretty easy career to me, but I always have loved the cooking/gardening/fishing combo in Sims3. He also has worked in the garden some and is level 4 at gardening, at level 6 painting, (I sent him to paint to keep him inspired for work), and level 5 mixology. He's chosen the chef branch so we'll see how that turns out. I found the best thing for his career was to keep him inspired so my advice is put whatever decorative items you can around wherever he will be that give off inspired aura. I have those lamps you get from having a lot of Sims3 stuff so used them everywhere. Prior to figuring that out it was thoughtful shower before work and painting.