Please do! I am just starting with some gardening and haven’t much experience yet.

Uh oh.

Well I'll just mention one thing... just. one. thing. Ok, no, let me do my top beginner mistakes, which seem to all be not understanding what plants need.

1. Over-watering. For example, tomatoes (and solanaceae in general) like periodic deep watering and shouldn't be overly moist. I always starve them for water until they start to get a little crispy (literally they look like shit) and do my weekly-ish harvesting the day before watering.
2. Not hardening-off starts. Don't plant those peppers in the ground without having them gradually outside over a few days, ending in being out overnight for a day or three.
3. Not understanding soil and air temperatures. It's super helpful to know the daytime highs and nightime lows and ideally soil temps as well. Some plants just really won't grow well when it's too hot (lettuce) or too cold (tomatoes, cukes, etc)
4. Growing starts in your living room window because it "gets lots of sun". If your plants are leggy and weak it's because they get sun for part of the day and it shifts around too much.
5. Assuming you have to nuke every living thing anywhere near your veggies. 95% of all insects are beneficials and if you do not provide habitat for them and/or you use copious pesticides, you are killing more good things than bad. On my last farm we used no pesticides, organic-approved or otherwise. This works if you have pathways of (ideally natives) for beneficials to thrive in. The classic example is flea beetles - they thrive in barren hot soil while the beneficials that would eat them avoid that. So plant your arugula near some grasses (like right up against it) and you will not likely have a flea beetle problem.