I will be as clear and plain as possible.
For the next several months, 6 at least:
Your answer is not to apply for more credit cards.
You should focus on paying all your current cards (you have several appropriate ones already)
Get to the point where you carry 0 balances on most, Paying in full, and letting one report a small amount.
This is a habit to learn and will serve you well.
At the same time, continue readin up here. Learn what a credit reporting agency is. Learn what a scoring model is. Learn the distinction between Soft and Hard Credit Inquiries. Learn what CLI is, and depending on your late payment, what a dispute or GW is. Learn what items (Beyond paying all your bills on time) effect your credit ratings.
Sounds like you are not in a terrible start - be careful not to make quick decisions that aren't best for you long term.
1) First, try to get SP CLIs on the cards you already have.
2) The minute your CapOne cards are at least 6 months old, combine them to get a bigger CL
3) When your true TU FICo gets above 600, you could try for a Barclaycard Rewards. Hubby just got one with his TU FICo hovering around 610-615.
4) SP CLIs are your friend! Request them as often as recommended (search around here on the forum for advice about that).
5) Don't bother with store cards (IMO)
Good luck! 