Most of the early levels you just build up sun buy buying a lot of sunflowers and sack a lawnmower or 2 then just place killing plants and use insta kill plants like chompers and cherry bombs potato mines and squashes for the Day Levels For nights you basically do the same thing just with the night plants but since you have the free Puff-Shroom you put most of them up front so scared shrooms and fumes can do most of the damage a further back. For Roof levels you never use the catapults since they take longer to kill so starting out you mostly do the same things until you get the coffee bean then you use the Fume-Shroom upgrade plus with garlic(once you get it) to push the zombies into certain lanes to damage all of them. I'm not the best by any means and have only ran the game twice but These are the strats that most people use if you want to see more details about certain levels I would watch Supers 2nd place run or watch him on twitch He talks during most of it so if there is any more questions you can ask during his streams