Carry Basic Tools With You
This varies for how much DIY work you do and how often you visit your rentals but it can be a real waste of time if you have to drive back home just to get some simple tools for a quick fix. Even if you're just there to sign paperwork having some tools readily available will save you time if something should come up.
Buy Extra Supplies
If you have to run to the store to buy a common item, pick up an extra or two so next time you need it you won't have to make a trip to the store. You'll have to apply this advice to the item you're buying and how far you live from your rentals (and how far the store is from a rental) but it's good to think about when you have to pick something up.
Have Spare Parts On Hand
Not all places have 24 hour stores and some parts have to be ordered. There are some things that are nice to have on hand for when something breaks at 10pm on a Friday. For instance a lot of water heater thermostats are the same, having one on hand could help you get a water heater back online quickly and reduce the amount of time your tenants go without hot water.
Communicate And Confirm
Miscommunication can waste a lot of time. To prevent that, clearly communicate your expectations and confirm the other parties commitment. You could waste a lot of time if you are to meet a tenant for a showing and you don't confirm they are going to show. If you commission work to be done and don't clearly communicate the deadline and expectations for it then it could delay a move-in or other work that needs to start, causing you to waste even more time managing the fallout.
Document Things When They Happen
Documentation can be a real help in collaborating and managing your business but it's not easy. The best way to have great documentation and save time is to do it when it's fresh in your mind and you have all of the details handy to record. If you toss all of your receipts into a box to worry about next year before tax time you're going to waste a lot of time trying to re-figure out what everything was for and why you did it. Plus you won't benefit from having access to real time financial data that you could use to make better decisions.
GovernRent can help you save time by giving you one place to keep all of your rental data. It allows you to create documentation system so it's not as painful to have good organized records and it gives you quick access to your data wherever you are. Don't waste time driving back to your home office to search through a stack of papers when you could have it all on your cell phone!