You want to straighten out your current situation, before attempting to add more to your debt pile. You will be rejected because of your current fair condition with a current creditor in collections. Once you're out of collections, and that bill is paid, consider same as cash deals - 6 months or 1 year and pay it off 2 months or more early, to avoid paying interest.
Also after you're out of collections, start a savings account, and start depositing $100 each week, while you rebuild your credit. 3 months later try to get a store card, if you get it, make a small purchase and pay off the balance when you get the bill the following month. Keep making those deposits. 6 months after you get the store card, check your score, and apply for a major credit card at your bank, where you've been making those deposits for the past 9-12 months.
If they grant you the account, buy something small, and pay the balance the next month, when the bill arrives (don't wait for the due date). The following month, buy something on the store card, and repeat the payment process, and keep making those deposits. 6 months later, buy something on your major credit card, and pay off the balance again, as before.
At the end of two years, check your credit score - it should be above 700 by now. If it is above 720, you might consider buying a used car, or making a major secured purchase, under 10,000 with a loan for 36 months, use the cash you've been depositing for the payments, but keep making the $100 per week deposits as you pay off the loan. At the end of the loan, you'll have excellent credit and the blemish will be almost history from your past payment problems, in another 2 years. You'll also have a nice nest egg, and have learned how to save, use credit and how to live within your means.