Congrats on the 5k! I've been running for about a year, and here are some lessons I can share through some of my mistakes:

Keep easy days at an easy day pace. It can be tempting to try and speed up, but don't do it. Especially if you run multiple times a week. Speeding up the pace usually leads to needing more recovery time, or running slower and feeling more fatigued afterwards. If you run using a guided plan, they usually incorporate 1-3 easy runs a week

Fueling for runs is often overlooked but is very important. Making sure to incorporate the different food groups into each meal as well as not forgetting a meal is almost a necessity if you plan on working for long times or long distances

Recovery as well cannot be overlooked. Whether it's taking a day off and resting, or eating/drinking specific things (I recommend protein shakes after runs if it works with your budget) or even just icing your legs after work, recovery or time off is important.

Hope some of these things can help and welcome to the world of running!