Basic Finances -- You should have a savings and a checking acct. This set up at the same bank as your credit lines: cards, mortgage, auto loans, etc. If possible have your paycheck directly deposited into checking.
Banking with one bank will open doors to lines of credit if/when you demonstrate credit worthiness. Credit worthiness is demonstrated by paying off obligations and keeping debt under control. At the same bank were I have my finances, I've paid off a mortgage, a couple autos, monthly credit card balances. I get offers everyday for refinance mortgages (reverse mortgage), credit card offers. My bank has extended credit lines to me: home equity, over-draft protection. I have onne bank with several credit lines that are managed like credit cards.
Pay off credit cards IN FULL at the end of each month -- so you're not paying interest on the balance.
I use credit cards for all purchases because I get cash rewards for using them. So far the cash-back rewards have netted me $650.00 -- tax free cash.
Credit agencies figure credit scores according to your "credit exposure." Being issued a $10K line of credit will lower your score if you can't manage $10K of debt.
I've worked myself into a position where I don't use cash for anything (except the purchase of legal, recreational cannabis -- where the shop can't take credit cards).
I keep track of the banking online. There's a phone app and a web site. Lately, since the debt is paid off, I've been moving balances into savings. My fico score is running about 840. This score gets me interest rates on credit lines that beat the credit card credit lines to death.
That said, I don't need to borrow money. Using a cash-back rewards card and paying it off in full every month is not so much "credit card use" as it is a financial strategy to make money by managing credit.
You don't need a $300 knife to build your credit. You need a bank that will set up a financial strategy for managing your money to YOUR advantage.
Running up a credit card debt -- even if you pay it off in 6 months without interest is not a good strategy for managing you finances and your credit score. Use your bank for credit lines, not some card you got in the mail!