Of course, without the University accepting you no point for you to read this anymore. So let us highlight a few things while you are planning to apply for studies in OSU (most of these details can be found in the Admissions web page; we're just re-iterating some important ones):
Undergraduate Application Deadlines:
If you are applying as a Freshman (aka JC, Pre-U or Secondary school students), your deadlines for applications are Feburary 2nd for Summer Quarter (Jun - Aug) and Autumn Quarter (Sept - Dec), October 1st for Winter Quarter (Jan - Apr) and January 2nd for Spring Quarter (Apr - Jun).
If you are applying as a Transfer (aka Poly, NUS/NTU/SMU undergrads), your deadlines for applications are June 15th for Autumn Quarter, October 1st for Winter Quarter, January 2nd for Spring Quarter and March 1st for Summer Quarter.
Although it's not a big matter, we often recommend you to start your school year with Autumn/Fall quarter, especially Freshmen, coz that's the most active quarter of the year and often you will find numerous parties and orientation events happening in Fall.
TOEFL, SAT, Poly and GCE 'A' & 'O' Levels transcripts
First and foremost, take your TOEFL (Test of English as a Foreign Language) and take it roughly around 2 months before your actual Uni application - results take 2 to 5 weeks to arrive and expires in 2 years. Don't forget to bring your valid passport (be sure it's not expired! Also, NRIC or any other identification won't do). To be safe you might even wanna bring your birth cert. Make copies of your TOEFL results before you send your original out with your application.
SATs are important for Freshmen applicants. Remember to make copies of your SAT results and take them with you too!
You can get original copies of your A and O Level certificates (statement of results) from MOE from their office at North Buona Vista Drive (near the MRT station). As for the Fab Four (Polytechnics), you can get more information about transcripts from their offices: NP, SP, NYP and TP. As with SATs, if possible, try to bring along at least have ONE original set of your college/poly transcripts or statement of results with you.
Money talks and bullshit walks
Even if you have a scholarship to cradle your arse, be sure that you have all the necessary bank statements, and/or proof of financial support before you even consider your application. That means enough money to cover at least 1 year's worth of studies and a stable income/guarantor for 4 years of studies. Estimated total cost of one Academic Year, or 3 Quarters, for an international undergrad is US$28,786 (est. for '03/'04, expect 5% ~ 10% increase in 2004-2005).
Admissions Essay
Ah yes, the one and only English composition that could make or break your application. So you may top the class in science and math, but if you don't know how to write better about yourself, you have a lotta work to do, mate. Luckily we can recommend a great place to start for you! Try the College Essays site from About.com. It has a few interesting articles for you to begin with. Search around the web for more information. And remember, plagiarism is criminal!