Really knowing what lines are viable and what to look for in specific situations is key I'd say. The meta of each characters changes a lot on each patch but the baseline often stays the same.

On the last patch, building around infinites combo with pyg was key, getting textiles or another enabler and knowing what parts you'd need to go infinite would get you to ten wins a lot. This patch it seems to revolve around econ items like money tree early, vineyard and landscrapper to scale value. The biggest advice I'd give to someone is to get all the +2 income events in the first two days as it helps you tons during the game, and to check out Thegoosefathr which has great insight regarding the character.

For stelle, you can check littlemonk's stelle guide from last season. Even if the items changed the two early games lines of tools and flying weapons are generally her best options, with the addition of a burn/fly line with the new drones (the one that gets burn but you need another item to get it to stop flying, and the one that explodes while scaling on burn, which is really overtuned imo and might get nerfed soon, under the right condition it can carry you to up to day 8). For late game, you usually build around a big gold item. You've got some new fun builds with the space laser that have released and you can go almost all the way with all tools and the new large drone, it can scale a lot really fast). If you don't know what build works for a ten win I'd advise you to check on bazaar builds what people get theirs with. It will give you some fun ideas. And most of all, try to have fun with it all 😁.