Without proper planning, this scenario can be incredibly difficult to complete. It is known to be one of the more "flawed" scenarios in the expansion packs that are nearly impossible to complete.
The issue is that new guests entering the park are initially sleepy or not very happy. Each new guest will drive down the park rating. It is important to place an entertainer in the front of the park and have it patrol only the first couple of 4x4 blocks selectable.
Make a double-width pathway from the entrance at a 90-degree angle to the left. Expand this pathway as the park expands. This will prevent the overcrowding problem. Allow space for double thickness paths throughout the park, should an area become too crowded.
Create two "food courts" with plenty of benches and inline paths separated by fences, along with every available shop and stall. The first one should be near the front and the other one should be near the back when the time comes.
Start with small rides, and build a roller coaster here and there. Jack up the prices to the highest guests will pay for the rides - for roller coasters, truncate the excitement rating and add a dollar - for large ones, people may pay up to $10. Once you get your park rating stable above 700, the rest of the scenario should be easy.
You may also want to delete scenery on the large pyramid in the back corner of the park - building and deleting a roller coaster through it can be very profitable.
Make sure to pay off your loan quickly, as the 14% interest fee can easily blow up your financial status and send your park into bankruptcy. Keeping it below $15,000 should keep the interest fees safe.