Some of this may not apply to you since you said you’re ok with the handling actors thing but these are the tips I gave a buddy directing his first thing:
-Patience, young grasshopper! Be (or at least fake being) as patient as you possibly can. I can pretty much guarantee you that you will be very, very short on time and constantly behind schedule and every delay, whether it’s an actor having problems remembering their lines or a missing microphone battery, has a tendency to try your patience. Try to relax as best you can, take a deep breath and know that you will just be behind schedule no matter how mad you get. Nobody wants to work for a grumpy asshole. Of course…
-On the flip side: try your best to be as assertive and “boss like” as you can. A nice boss mind you but still, you are the one in charge and you need to project as much. As cliche as it sounds, you aren’t there to make friends. I know that sounds counterproductive to the patience one but it’s a tightrope walk. You want to encourage artistic freedom and a sense of fun/play but you also don’t want to go home empty handed because everybody fucked around all day. Constantly remind yourself for the reason you are there: to create the best possible finished product.
-Speaking of “being the boss”…make sure you are prepared for it. Everybody will come to you with questions. From “how should I deliver “I’m sorry”…should I put the inflection on “I’m” or on the “sorry”?” to “where do you want the camera for this? How many angles do you want?” to “which color towel should he walk out of the shower with?” (seriously)…know the answers ahead of time as best you can. Nothing instills less confidence in an actor/crew member than if it seems like the “person with all the answers” has none of them. Of course you won’t actually have all the answers all the time so just be good at thinking on your feet and pretending that’s what you wanted the whole time. Practice saying things like “no, not that fake mustache, the other one” with the utmost confidence. Be as detail orientated as you can stand/afford.
-Probably the most important thing I would say is just respect everybody, treat them well and try to relax as much as you can. I guess that’s kind of the same as the first one but it really can be a super fun and rewarding experience to put together a fake world for a bit and be the ringleader of your band of misfits. Try to focus on the fun parts and not how goddamn stressful it is.
Also, I think I said this in that mess of words earlier but always keep focused on the end goal. Try to edit everything you are shooting in your head together as best you can. When you visualize a scene does it cut to a close-up on a certain line? If so then make sure you get that close-up. Even if it’s 3am and everybody wants to go home…don’t settle. Get what you need to put together the vision you see in your head as best you can. Of course compromises will have to be made and everything won’t be perfect but know what you can and can’t live without getting before going in as much as possible.
Last but not least: you will fuck something up. I guarantee it. Everybody does. Take it in stride and learn from it and don’t beat yourself up for making a “rookie mistake” because well, you’re a rookie.