Best option to rebuild?

I’ve made a recent post if anyone wanted to go back and look more in depth at my current credit situation. But my current Experian score was 507, paid off a collection, and got it removed and it went on to 509. I’ll take the wins where I can! But I’m planning on paying off $5k in collections this year, and well as $16k worth of personal loans. The only bad thing I see on my credit (according to credit karma) is missed payment percentage.

My plan was to get a secured credit card and deposit $1200-$1500 on the card. Then use it to pay my rent/ or groceries every month, then once the statement posts, pay off the entire balance. And keep doing that month after month.

I do not have any other credit cards. The only “good” things reporting on my credit is keeping up to date on my two personal loans.

Is this a good idea to build a higher credit score? TIA!