More visitors:
When you are in Dinoland, just ignore or delete the message about the cheap gate price to get a lot of visitors.

Hint: More money:
Start a small park with four puzzle games close together, two rides, one food, one bathroom and a gate price of $0. If you set it up so all four puzzle games are within view of each other, you can do the global price raise/lower for all puzzles while all four are active (making $40,000 at once) The $0 gate price will get the visitors in fast. Set the prizes value to $10 and a maximum win possibility. That makes the visitors happy, stay longer, and play more.

If you need to take out a loan, take out the least amount of money. Then later in the game, when you have a little bit more money, take out the $30,000 loan (or the highest one) and pay off the first loan. You will still have enough money to buy rides and attractions without going bankrupt.

Hint: World of Wonders park:
Collect three Golden Keys.

Hint: Space Zone park:
Collect five Golden Keys.

Hint: Better park operation:
Assign staff members to a certain area. This way the park is cleaner, rides are fixed faster, and more people get to see entertainers. Note: Put a staff room in each area.