Hi, First of all, sorry if my English is not perfect
if your credit is poor there are many things that you can do. 1) first and fastest is being someone's with good credit history authorized user.
2. pay your bills on time. 3) pay off your debt in your current credit cards. 4) never use more than 30 percent of your credit line, the lower the better. 5) pay your total balance before your closing date on all your credit cards 6) try to add your bills to your credit report. Experian has a booster option that you can do it. 7) Ask your home owner, if any, to report your on time payments to the credit bureaus, if you have not paid your rent on time, reporting it will lower your credit score. 😎 install Credit Karma app and check your vantage score for free also you can get your Fico score from different valid websites one a year (like Experian) so you can understand what is wrong. sometime there are some wrong information and you need to dispute it. 9) regularly check your credit report. 10) if you have less than 5 credit cards, apply for a new card (never apply for several cards at the same time) but I highly recommend that you do the first 9 ones before applying for a new card since you might get a rejection due to your bad credit score. opening a new account with a bad credit score won't help much. I am sure if you do all I explained you can build your credit in a year.
Remember, you can use your credit cards for everything but you should do number 4 and 5 above every month. if you do it definitely build your credit not hurt it. Good luck