I was waiting for orhers to chime in but heres my tips.
You could notch out the unwanted target numbers, might help. The trouble with aluminium (especially canslaw) is youre going to get it overlap with good ids, gold rings, goldies, even predec coppers at times. Its a challenge we all face , you either persist and dig hoping to be rewarded, or notch it out and try and avoid the worst of it.
Alternatively you can use pinpoint made to check the size of target response. With a 50c piece vs a bit of aluminium this should give you a rough idea of the surface area of the target. In time you will get better at this. Deep flattened cans can come up like goldies or higher, but pinpoint will show you its a very broad signal.
Same applies for beaver tails, they tend to make a sweet tone/id only swung one way and the cross section of the signal is very small, when its larger cross signal thats solid its more likely a 20c.
Lastly swing 3 directions, N/S, E/W, Then across the centre of those. Most of time (you can get clipped ones, on the side, or as youve seen in a spill) you will get a solid response across the directional swings with coins, making it much more likely a coin vs junk.
My plan is based on location. If its a busy place, I cherry pick. If its somewhere close to me, I hunt it out. If its some distance from me, I start with cherry picking, then looking for the unusual ids that are solid. If its just a playground the odds of ring pulls is high and rings low, so I forget the 5c and ring pulls. If its a picnic area and people spend time in it (especially lakeside areas) the odds of jewellery is higher so worth it. If its trashy then reach for a small coil and up the recovery speed. If its deep ground turn up sensitivity.
Maximising the treasure is the aim of the game thrse days, so taking the easy wins is always first priority. Spending 2 hours sifting through junk is the same as giving up an hours travel and 1 hour picking up goldies.
That said the more you dig the more you will understand the machine and whats under the coil. No way around it you will miss good treasure if you dont hunt it well, and the fastest way to learn to dig less crap later is to dig more now. By going down the dig road you will pretty soon just by tone and id confidently and mostly accurately call it out before youve dug it.