i've helped a few a work gain points once I learned the game. If its the only card. Use it as a debit card. Pay it off every payday. If its the only card. Pay it off before the online "due date" and leave 1-5%, or 10-15 bucks. Few days later Cap1 will post the statement. PIF. Repeat. After 90 days hit the luv button for a SP CLI. After 6 months. Go for the next Cap1 card, cash back preferred taking you have the Platnium now. They like heavy usage and PIF except the 1-5%. For FICO 1-5% statement posted. Please 2 at one time. Just read my siggy below. I had zippo in cards after BK 11/15. Now its a beautiful thing for me. JMHO.
Whicever one you got. Its the same game. Their new rules are 6 months between new card apps. 90 days for new accounts for a SP CLI. And 6 months between approved SP CLI's. I got in right before the new rules started in July. Secured is a bit different, but it will raise your chance for a unsecured in 6 months like the poster said above.
@Cheryla18 wrote:
@KillerWaves wrote:If it's secured just use it like normal, pay it in full and apply for a QS1 after 6 months. Used to be less than 6 months a few months ago, but it's 6 now according to what I have read on here. When I got the QS1 I had a very low limit about 1500. I spent 2-3K a month on it and paid it constantly after purchases with very small balances (5%ish). They gave me almost another 4k CLI after less than 3 months of that decent use.
If that 300 CL card is a secrured, dont even bother with it. You'll be lucky if it hits 500.
It the Cap One QS i believe... I had a choice between the QS or the Platinum and i chose the QS for the 1.5 % cashback.
If it's the one with the annual fee it's the Quicksilver One, which is actually identical to the QS (other than the AF, of course).
My own QS MasterCard used to be a QS1, and it also started years ago with a $300 credit line. (In my case it started off as HSBC, but was later converted to a QS1). Since it was still at a modest $720 credit line when it became a Capital One card my data points will still be relevant.
Like many others on here will attest, with my two QS cards Capital One has been very responsive to swipes and usage... the more I used it, the more cooperative they were with raising my credit line. Especially when I was starting out (and had limited options) Capital One seemed to grow more with heavy use, relative to my credit line of course.
When my credit line was small I would at times max it out multiple times each month (making payments every week or so) but this isn't required for it to grow, only if you want to use it to spend more than your credit line. My QS card that started off with a $300 credit line now has a credit line of $4900, and would probably be higher if I used it more often. My newer QS Visa card has a credit line of $10k, so once you're more established don't be shy about applying for a second card with them; they can be generous even if your score is less than perfect.
Hope this helps! 
P.S. If you do have the QS1 (with the annual fee) be sure to remember later on to ask about changing it to a no-fee Quicksilver... some people have got them to do the upgrade after only a few months, but others (like myself) had to wait longer. 