So,I just got RCT 1,2,and 3, and ilike some tips on how to use them.

I mostly play RCT 1 and 2 nowadays, and here are some tips I can give you:
1. Cluster your food stands together in plaza like areas. Having food, drinks, and bathrooms all nearby can save people time and energy in getting to them. I would also suggest building these "plaza's" off of main paths as these areas tend to get rather crowded and can make your guests unhappy.
2. Never build paths more than two tiles wide. Due to the simple nature or RCT1 and RCT2, the guests' programming allows them to easily get lost in big open spaces.
3. (RCT2 only) For extra support structures (such as making wooden coaster supports look realistic) I would highly suggest using the six flags triangular supports along the taller hills on a wooden coaster.
4. For RCT1 and RCT2, variation is key for scenery. Using different textures on tiles can look a lot more natural and blended, especially when zoomed out a bit. Trees can usually consist of just a few types, but ground shrubbery is also very important.
5. Mostly for RCT1 and RCT2, building lots of shuttle coasters is the easiest way to win scenarios. They can usually get pretty decent ratings, bring in more guests, and rake in lots of cash as well.

For coaster building
You'll notice that there are 3 ratings for each coaster, which are Excitement, Intensity and Nausea
In RCT1 and RCT2, focus on keeping intensity low, if it gets over 11 or so, guests won't go on it
you can do this by making it go over inversions slowly, and bank turns where it is fast
In RCT3 the popularity mainly depends on the excitement rating, to get a higher rating, make tons of hills, add scenery, bank turns, a couple helixes, and all should be good
When pricing, if you have a park where it is pay per ride, originally charge the amount that the excitement rating is, in all 3 games, however over time guests will eventually find things too expensive
To make more money add on-ride photo sections

Other stuff
zone your staff, especially handymen, to improve the park rating
keep salty foods near drinks
dont build launched freefalls or roto drops too high, the intensity rating skyrockets with height
If youre making hills, and you know it make them in scenario editor, as in the land tool when youre down to a 1x1, you can press the minus button again and the hill will rise with it
Have an information kiosk at the beginning of the park
make sure there are plenty of washrooms, first aid, and cash machines (if money)
Have fun!

I mostly use rct 3 because i can play sandbox mode

Is no one going to mention custom content?

Is no one going to mention custom content?

maybe later. its probably a good idea to experience the base game first, then start with CS and open his/her eyes to how awesome it is

Is no one going to mention custom content?

Ok so what is that

Is no one going to mention custom content?

Ok so what is that

custom content is a wonderful thing. it makes the in game content feel really restrictive.

you can get new cars for tracks, loads new scenery items, and so much more. just go to the 'downloads' section of this website and look around

I would highly suggest getting some CS, but first, as Super Moose wrote, you should play around with the default game first and get some experience. CS can be a bit overwhelming at first so you should iron out the basics of the regular game first.

Is no one going to mention custom content?

Ok so what is that

Custom scenery are items that people have made to add to the scenery items already in the game also abbreviated as cso (custom scenery objects). There are also ctr (custom tracks) and cfr (custom flat rides). There are many tutorial on youtube on how to install and use cso, ctr, and cfr. I can help you with somethings. Here is a good one by Silvarett RCT3 Tutorial - How To Find & Install Custom Scenery
https://www.youtube.com/watch?v=fU0mukcrmBc (If you are on a mac it may be different then just to a search on youtube "how to install custom scenery on a mac"
Another good video by Fluxtrance
RCT3 Tutorial - How to Install Custom Scenery
http://youtu.be/dG9hLcv5MgI

I would watch some of there videos on the work they created to as inspiration. I also started playing RCT3 with just in-game content to get familiar with the game. Oh, by the way here is a link to a site where most people get there custom scenery content (cso/custom scenery objects)
The Custom Scenery Depot
http://www.customscenerydepot.com/
I'd also be willing to help as well.