The first thing you need to do is pause the game. All of the rides are free, which is losing profit. However, putting prices on certain ones will draw away customers, saying it is 'too much' (i.e. All the Scrambled Eggs, Merry-Go-Rounds, Observation Towers, etc.). Demolish all of them and replace them with more modern rides (you can replace them all with Observation Towers, since they lose value slower). Charge $1.00 for all gentle rides/thrill/transport rides and $2.00 for roller coasters. This should net some easy profit, but there's another problem.
Your loan starts extremely high, totaling $4 million! There is no way you will be able to pay this all off, let alone a million (I, for one, only was able to cut off about half a million.). The good part about this is that you can increase the loan as high as you want (needs confirmation) whenever you are short on funds. Though the interest rate will keep knocking you into the negatives, it will go away fast. Don't worry about money yet - read on.
Build new roller coasters in the cleared out areas. This may require removing some current rides (the roller coasters will earn more profit than the rides already built). You start off with the two necessities: Steel Corkscrew and Steel Roller Coasters. These are good because they are compact and earn profit. You may have to custom-build some, but it shouldn't be hard as long as you don't go overboard on G-forces. Remember that coasters can be built atop the high-leveled ground (like the land near Limit), and can go underground as well. Use the Steel Roller Coasters when you have lots of space (since they have in-line twists, which increase excitement), and Steel Corkscrew Roller Coasters to make easier, more compact coasters, due to the fact that they have Powered Launch Mode. One pre-made design, usually titled u3809 or such, is compact and cheap, though make the launch speed 42mph to lower intensity. Custom-built coasters should not have more than 8 inversions, or the intensity will be too high. Building plenty of short, efficient coasters will massively increase profit and guest satisfaction. Doing this will enable you to lower your loan faster, making your company value better, even if only slightly.
Since guests will start filing out fast, rely on advertising campaigns with your money. Putting all 5 (since you can only do free or half-price entry, not both) campaigns into effect can yield hundreds of new guests. This can also raise up to $20,000 in park entrance fees. Use this money to also hire LOTS of new staff, since the park is so huge and requires lots of maintenance. Set patrol areas for each worker (especially Handymen - it may be wise to set two per 'area' of the park, just so the clean-up will be more efficient).
This scenario is easy if you know what to do. You should never leave the scenario running, just in case your handymen do not do their job properly (I suggest always keeping 1-2 open on the screen to place them on areas that need clean up). Since guests file out quickly, either lower your entrance fee a bit (they will say $60 is cheap, but this leaves guests with only $10-40 for rides!) and/or advertise constantly.
Scenario Guide by MkWii17