okay here my tips
1. it seem like you caring you resource and lost it all if you went mining Always have a ender chest ready if you at the end game but early game kind of hard but if you are always caring stuff i recommend only caring like 6 diamond as most if you are planning a long mine trip
2. mending is really easy to get sometimes what i usually do is kidnaped a villager from there home and lock them into my dungeon and kept forcing them into a liberin and if they don't got mending i break it and keep replacing and once i found it i immetdly buy and if it HARD Mode i turned them into zombies and curing them it makes them turn dirt cheep!

3. to get stuff more faster look up the ingots you want to get which y level spawn more and strip mine it the best way imo unless you have any mods like create mod i recommend making a drill
and yea that all i think!