Strategy 1, by Figmeister
This one is a fun one. Basically, you want to keep all of the cars as they will boost your park rating and start building! You should delete a few cars and make some flat rides, but block off the rest of the paths, make some stalls, and get to work on some coasters, because time is literally money here. Get rid of the path around the park, and the marquees if you need money. Also, get rid of the stage. The objective will be challenging if you aren't experienced and just starting. Since you only have until Year 2, you must run lots of advertisements and build lots of cool roller coasters. If you are experienced, this will be very fun. Just build everything without making the park to complex.
Strategy 2, by John-Mahmud
You should attempt to keep most (if not all) of the cars in the car park for reasons stated above, but feel free to take a few of them off to build one or two flat rides, in order to keep your guests occupied without wandering aimlessly looking for rides.
Build a Shuttle Loop for a quick buck, make sure it doesn't crash (obviously), and put a max-length train as well as an On-Ride Photo Section for an added buck per dispatch.
Build some shops there to keep your guests fed and catered.
Cut the path going to the back of the park towards the marquees, and delete some of' em if you need some fast cash.
Build a big roller coaster with lots of capacity (a Giga, Twister, or a Corkscrew might do the job), and make it roll through the stage for an easy excitement bump. Make sure it can roll several long trains, and use block brakes for safety. Place the station either near the car park, or behind the trees, towards the stage. If you do so, then keep the space going from the park entrance towards your station -behind the circular path- empty : You will be able to build a Bus Tram line there for fast transit between the park's entrance & the big coaster's station.
From that point onward, build new rides as will, but avoid opening the whole path around the marquees and also avoid using the space towards the scene for stuff other than your big coaster or rides' tracks. You should hit the objective without any problems if you followed this strategy.
Strategy 3, by C-Down Shine
This scenario can seem daunting, due to requiring 1500 guests in half the time Crazy Castle gives you, as well as being a pay-to-enter park. Start off by setting research priorities to Shops and Stalls and Thrill Rides, with maximum funding. Then clear out all the cars and the stage for money. Additionally, cut off the paths that lead to nowhere for the moment, as you don't want staff or guests getting lost. Build some gentle rides near the entrance, and additionally a shuttle loop Corkscrew Roller Coaster(Revertigo works extremely well here), but leave space open to build a transport ride. Have said transport ride lead from near the park entrance in a giant loop around half of the main area(don't have the ride go into the stage area), with only one station, for now. Once you've researched the Lemonade stall, shift your research priorities to Water Rides only to get the Log Flume, and then to Thrill Rides and Roller Coasters. Keep expanding the park in two branches from the entrance, and build stations on the transport ride in a way to facilitate guest movement between the two branches. At this point, set your entrance fee to $35, and keep it there for the rest of the scenario. Keep adding untracked rides whenever you have the cash.
By the time year 1 ends, you should have 750 - 850 guests(if you don't, you're in trouble). First, if you haven't already, start advertising the park, and do not stop until the scenario is complete. Now build a high-capacity roller coaster with an on-ride photo section, even if you have to take out the maximum loan($10,000), and advertise it. Use block brakes to guarantee the ride's safety and increase the capacity. This will greatly help your income, in terms of both photo sales and new guests. Continue adding new rides throughout the rest of the year, and never stop expanding and advertising. If you haven't hit 1350 guests by mid-September, then start advertising every possible option for 6 weeks. By the start of October, you should have one of every kind of thrill ride and most of the gentle rides in the park, and stop research at the start of October to avoid using money that you could advertise with.
Don't spend a lot of time meticulously building every ride. What's important in this scenario is the number of rides. Remember, regardless of which strategy you use, never stop expanding and advertising. You have more than enough space to build whatever you want, so guests won't complain about overcrowding until the end of year 2.