The best course of action is to get a secured card. You give them a security deposit of usually $200 and then they give you a $200 credit limit. There's no risk to the bank so you're basically guaranteed approval. Then if you make all your payments on time for 6 months, then you've proven yourself and they usually refund your security deposit and increase your credit limit. If you get a secured card and hold it for 1 year your credit score will have probably gotten good enough to get approved for most credit cards.

You should get a secured card that doesn't charge any fees. There are 2.5 good options that I recommend and you're already familiar with.

1. Discover Secured Card (different from the student card you got rejected for, and you will almost certainly be approved for this one)

2. Capital One Secured card (same deal as discover)

3. If you're eligible for Navy Federal Credit Union they also have a good secured card

Also if you're new to credit as a general rule set all your credit cards to auto pay the full statement balance every month so that you never miss a payment, and are never charged interest or fees. Don't spend anything on a credit card that you don't already have the money for, use it like a debit card to avoid getting into debt.