I’m sad this is too far away for me to help with actual in person filming. But here is some advice (the voice of many year’s experience).
Plan the hell out of it. Planning, and setup takes the longest of any part of the filming process. Don’t be afraid to storyboard to help once you have a script. Shooting is fairly quick in comparison. Don’t get discouraged as you plan! You’ve got this!
Always choose practical effects over digital/ special effects. Practical effects look real because they are real special effects, even when done perfectly, still leave a bit to be desired. On a budget, you won’t have top end special effects.
“Fix it in post” is not a real thing on budget films. Get it right in on camera. Don’t be afraid to do multiple takes and get multiple angles. Get more footage than you think you could ever need. It is always harder to reorganize and get people back for reshoots than it is to spend the extra time to get that one shot that you think could work better.
On shooting day have one person who’s entire job is continuity. There is nothing more jarring than a person’s hair braid switching shoulders between shots or that guy in the background being in the wrong place between cuts.
Oh, and be sure to record CLEAN audio. Grainy/ blurry footage can be a feature... bad audio can literally harm people’s ears and totally destroy an entire production.