Putting money in a business bank account SMLLC

Good day,

I am a photographer in Colorado. I started an SMLLC and never put in any start-up costs. I made enough money selling prints online but now need to add additional funds to my business's bank account. I want to be able to purchase supplies/use it for purchasing prints to sell and be able to write off the costs at the end of the year. I am assuming the best way to do this is via business equity. Is there anything special I should do when I put money in to make sure the government does not think it's profit from my business, and would this affect tax right-offs on schedule C in any way? Thank you