What plans was it based on? If it wasn’t plan built you need to calculate where the CG should be on the wing and get that right first, with all the electronics and battery in situ. I am slightly concerned you are finished building without servos etc at least fitted, since most kits build around those unless they have access panels.
An empty airframe won’t balance or glide at all well, everything is designed to require some nose weight at the least. Most kits designed for RC will be assumed to have RC fitted to balance.
First establish where the CG is going to be, usually it’s near the wing main spar, soneone clever on here may have a way of working it out if you don’t know where it is.
Get your electronics in, test them on the bench first WITHOUT A PROP ON THE MOTOR, get the servos centred etc. Then fit it, ensuring you have all the control surfaces as flat as possible at the middle position to minimise trim problems.
Now CG the whole set up, be meticulous about that, just a touch nose heavy, no more than a few degrees off level. There’s a couple of good FT videos on pre flight checks and CG, watch them.
Now you want to set the rates on the control surfaces, set up low rates first with a switch if you have them, then high rates. If you don’t know what your airframe rates should be then set to a similar FT gauge, print it off the plans. Set the low rates on your ailerons to under 50% total throw if you are learning, I found that much easier.
You will want EXPO if your transmitter has it, 30% minimum on all three control surfaces, I set 50% expo on my ailerons as I am a clumsy pilot.
Rates are important, they stop you having huge control surface movement when you are not ready for it.
Make your test flights on low rates with expo on. If you have mixing on the TX put a little elevator on the ailerons, 10-20% as it helps keep the nose up.
If your TX lacks expo then look at the FT stick limiters they made, they physically stop you throwing the sticks right over/up/down.
Once it’s all CG tested and the rates are done, find a space with nice soft long grass/weeds to test glide it, throw it and see what happens.
Do a RANGE TEST on your kit.
DON’T TRY AND MAIDEN IN WINDS OVER 10mph.
If all that works then try taxiing if you are going to ground launch, practice getting the tail up and see how it goes on the ground, dial in your undercarriage toe in so it tracks straight, you might have to compensate for the thrust angle of your motor with the rudder.
If it’s a belly lander then you can skip that and try a flight, I did a few short hops in my tall weed test field first to see what trim and thrust angles I was going to have.
When you first fly it for real, concentrate on going UP first, climb at least 60-100ft before trying to turn, if you have a buddy to hand launch get them to gently throw from the CG not too far forward/back and don’t launch at full throttle. If you don’t have a buddy launch with your left hand (mode 2 control) so you have elevator control.
When you go high then you can trim the controls. I found this order most helpful, from an FT video (again!)
Elevator
Ailerons
Rudder
If you struggle to fly without total hands on sticks, stay really high to trim, then you have room to panic. Flying high is not a problem, get used to the handling a bit before trying to land, I found it better to sort the trim in flight and not try landing with it incorrectly trimmed, vs landing then messing with it, then trying again.
If all this fails and you get a pile of smashed parts again, try a FT kit or set of plans, something a bit more forgiving like a Tiny Trainer, Sportster, Scout, Cub or similar. They are cheap and simple to build and all the complex work of sorting out handling and CG etc has all been done. It’s much easier to learn to fly first, then mess with personal designs, than the other way around. I have been building tons of other models for years and I found both kits and plans much easier to get help with as so many people had built them already.
Hope this reduces crash time!