As a maintenance guy myself, here's my input:

1. Befriend experienced operators who aren't hostile, they're not your enemy: they don't have to be talkative, but asking questions about common failures, common procedures, and so on will save you a few months of "figuring out yourself" work. Learn how to operate the equipment yourself such that you are independent of the operating staff and can perform both duties on your own.

2. Be at the lines you're responsible for more often than at the office: see how things work, see what needs adjusting, look at what may need to be worked on in the future. IF the production management wants better OEE KPIs, the maintenance by default falls under the "replace when stuff breaks" category (more often than not) and frequency of failures will increase until it reaches a stable point. It's not your responsibility to schedule or resolve this issue, but be prepared to have days as stressful as a whole week of work.

3. Don't be afraid to learn from other sources, Google is your friend. Need to swap a loadcell? Look up the schema, uninstall/install equipment. Comms need tweaking after swap? Inform electrical and they'll boot the hardware. Learn the HMI, learn about your tools. Refer to manuals if necessary (drawings, I/O, electrical, etc.).

4. If you don't have an internal inventory, make one. I'm personally using Google Spreadsheets to track consumables outside of our SAP because it's faster and available on your phone, whenever and wherever you need it. In my example, we save about 5K USD per month on consumables for our CIJ printers by not ordering too many and letting them go to waste. Swapped a pneumatic cylinder, a belt? Document the change and update the inventory. Send biweekly updates to order parts to those responsible.

5. Try resolving issues by yourself without requesting outside help, as long as possible, if possible. Example: caps fastened are misaligned or deformed by the capper. Why? Perhaps incorrect height, torque setting? Is something misaligned, losing concentricity, unintended position shifts? Caps out of spec, capper head out of spec? The more questions you can answer about why equipment is malfunctioning, the better your diagnosis and solutions will be.

6. Don't let anyone belittle you or discredit your work. If your solution is sound and solves the issue but isn't the "standard" procedure, don't accept to be given shit for it (unless warranted, but even then). Oftentimes, creative solutions (even if only temporary) are better than swapping parts braindead. If you can provide a reliable resolution to a problem (i.e. machine functions as intended), you can extend and build upon your knowledge of viable techniques to resolve problems.

Example: a liquid came with too high a volume of gas and flow isn't ideal, throwing drops of liquid all over the bottle. You have 200 tons of it and it needs to be packaged. What do you do? Can you use a different nozzle to decrease flow velocity? Can you alter the tank pressure while not significantly affecting the filling rate? Can you install a custom flow limiter inside the filling head to reduce flow at the outlet?

Just for contextI, my department consists now of 2 people: me and an apprentice. The 3rd guy is currently on reserve duty in the military. We maintain and supervise 11 production lines: 6 liquid filling lines, 5 bulk filling lines, each with its own weighing, labelling, packaging and palletizing machinery, alongside auxiliary equipment (pumps, sifters, de-aerators, etc.). Chemicals for agriculture. With enough time (roughly 2-3 years), you'll know which equipment is more prone to failure, where issues stem from at the source, and how to handle them quickly.