How have you utilized algorithmic investing for your trades?

For some background, I’m probably the typical retail investor, but I tend to shy away from the “meme stocks” and have more of a buy and hold strategy. I tend to invest in what I know and what I’m comfortable with (SPY, Apple, Nvidia, QQQ, and some other ETF’s in industrials and retail). Over the past year I’m up 23%, but I’d like to be a savvier trader and see if I can maximize my gains further with shorter holding periods.

I’m currently learning more about algorithmic investing and I want to understand and gain ideas from others experiences. Has anyone here been successful developing their own algorithmic trading models to initiate trades? Or do you prefer to use third party resources?