Giggle Downs is already a decent park, but RCT1 players should still lower the entrance fee to $20 for now. People aren't as poor as in the previous scenarios, so it still can be raised again after further expansion.
Research should be set to Thrill Rides (since Roller coasters are already covered here) and Gentle Rides after.
First start would be hiring additional staff, since 1 mechanic and handyman is far from enough to cover all. Now players should reduce the Ferris Wheel rotations amount to 1, and increase the maximum allowed people on the Spiral Slide to 5 (if kept in place, since it would do much better moved to a 3*2 spot to make some room). Further moves would include reducing the maximum waiting time on the Steeplechase rides to 10 seconds, since they are synchronized and force one without passengers to create unnecessary waiting times. Since a breakdown can cause the same problem, having a mechanic patrol exclusively around those four rides, would be a must do. The price for the extra mechanic here, is far worth it.