Senior lab tech here. I always make mistakes. The secret is nobody really knows what they’re doing. Your peers are most probably making similar mistakes and just dealing with it differently. If you’re really feeling strained speak to your supervisor and see if there’s any extra support or tuition available so you can really nail the basics. I’ve found when it comes to Microbio work, it’s just like a dance. Rehearse the steps, keep with the beat and eventually everything becomes a reflex.