I feel others have said what I have to say but I want to chime in anyway Start small, be realistic, don't go in expecting the world. When I was 17/18 I'd always dream big and go into making a map with the intention of it being the greatest thing created since the statue of David's ballsack or something. The further in I got with my projects the more I realised I sucked and got super frustrated at what I was making because I was just biting off more than I could chew. My vision outmatched my abilities and I refused to accept that. So if I could go back and give my aspiring idiot ass some tips, downsize and get rid of that ego and just release it. Small maps or whatever, and level up as you go.
A good example of my younger thinking was Half-life Nightwatch was all the rage back then in the HL1 modding community, It was the Duke Nukem Forever of mods and everytime they released screenshots I got really disheartened with my own work and just binned it and started over. I was always comparing myself to people with far more experience and ability at the time. What I should of done is ignored all that and focus on my own creations and work on my skills rather than looking at what the best at the time were doing. I even remember applying to Nightwatch at one point as an LD, I sent in shit tonnes of my work hoping they'd take me on but they ultimately rejected me citing I wasn't quite up to the standards they required. That really stung as I thought I had the abilities to match their amazing work, but alas no. That was the spark that ignited me to really drive myself and improve my skills as an LD.
So yeah, moral of story, finish what you start. Don't be afraid of negative feedback. Don't get distracted by what others are producing. Don't bite off more than you can chew and be realistic with yourself.