I've been playing pixel dungeon for about a week. I know, it's nothing compared to some of the veterans here. Don't judge.
Anyway, I already like PD quite a bit, and I think it's a really cool game. However, I have one problem.
I can't even make it past depth 3!
I've been thinking about my strategy and what I do. Every time I enter, I always completely search the entire depth and take any loot I can. The only rooms I usually ignore are the piranha rooms (cuz they are wayyyy dangerous and I've died to them 3 times already) and the barricaded rooms because last time I tried to open the door by throwing all of my potions (which were unidentified) at it, and I ended up losing half of my health to poison gas, wasting all my potions, and not burning the barricade down.
Every time I die, it seems like some stupid fluke. I've died by opening graves and getting trapped by the wraiths that spawn, opening a room, taking one step, and then activating a summon trap and being pummeled by the sewer crabs summoned, three sewer crabs by chance spawning in front of me on depth 2, being surrounded by knolls scouts, accidentally drinking a poison gas potion, drinking all my potions in a last-ditch effort to not die and ending up dying paralyzed, on fire, and poisoned, etc., etc....
I'm not sure what to do anymore. Whenever I feel like I'm geared up and ready for anything, I get killed by a trio of sewer crabs or something. Please help!
Sounds to me like pretty standard PD experience. You're on the right track with searching everything, though I think you missed the point of some of the special rooms:
• The piranhas are absolutely busted on purpose - you're not meant to be fighting them most of the time. Whenever there's a piranha room on the floor, a potion of invisibility will also always spawn, so you can take the loot safely.
• Barricaded rooms are similar business - so to test potions, explore the entire depth first and use the ones you find first. (Related - to exit a cloud of toxic gas, move diagonally, and preferrably next to doors.)
• Wraiths are a harsh lesson the first time, but now you can use the knowledge on how the graves work to your advantage; a wraith will not appear on occupied slots, such as when you stand next to a wall. Then simply lure them to the nearest doors for a guaranteed surprise attack (which should be the way to start any fight).
Most importantly - just keep at it, and eventually you'll see yourself getting better.