I have very limited credit history. I started this January. I read that I have to get a few credit cards to build credit history. I have a secured card from Citibank which only has 200 credit limit. A Citibank secured loan for 500. Bank of America gave me 4000 CL for A Worlpoints Platinum Plus Credit Card. I have a ChaseFreedom Mastercard too. Thing is I'm preparing my credit history for a car loan. I applied for other credit cards in one day and got a few rejections... reason being having too much inquiry ( ok, i know i should have not made too many applications but i figured to just do it all at the same time) and too low credit line. But I never missed a payment, I only use 30% of my credit line and pay off more than the minimun balance.
Questions :
How bad will these inquiries affect my chances of a car loan?
How many months should I wait to have this fixed?
How can I increase my credit score?

Thanks! :-)

You don't need that many credit cards to have credit history. Just one or two is enough. Keep paying over the minimum balance on each, and you should be set in a few months, assuming you don't have other negative items on your credit report.

My wife and I learned how to clean up our credit at "thecreditrepairmanual.com"

Here is a good article about repairing credit score http://www.badcreditresources.com/fix-your-bad-credit.html
I hope you will find it helpful!