Okay, so first, I need to warn of some flaws and glitches that may cause you some troubles.. Some of these may contain spoilers to later levels, which aren't that big actually. Just enemy types and such.
FLAWS!
--> When you level up, -ALL OF YOUR STATS WILL RESET AS IF YOU ARE NAKED-.
I cannot stress this enough. It took me a while to realize this, because in the higher level areas I would look forward to leveling up, since it would be like a free heal (more on that later). I seemed to noticed I would take huge amounts of damage sometimes though, and then I finally found this out. The only way to fix it is to change maps. Switching your gear off and on will not help.
--> It is very, VERY hard to get money in the start of the game.
Because of this, you will almost never be able to afford things that aren't absolutely needed, such as armor and weapons. And yes, the 5% damage and magic increase items are next to useless. Good thing is you can sell your old gear to help afford the new. Thankfully they help a lot. You will go about 95% of this game without using potions, since it's a giant cash sink. You will almost always be saving up money, and the cheapest way to heal is always the Inn, especially toward the end.
Your best bet to get early cash is just to get eggs. All eggs in the game, yes all, sell for 25g. At the start, this is pretty awesome. In the end, very annoying. Thankfully, for some unknown reason once you get to the second to last level, getting money becomes a joke, since the ice shard sells for so much.
--> You have very little item space to work with.
This doesn't seem like a problem at first, but you will be stuck with those 14 item slots the whole game, wearing gear, carrying shards, carrying quest items... You have to manage it well. The only tip I can give is once you are able to slowly start completing a gather quest, you may want to do it as soon as possible. being able to sell that item is much better then being forced to hold it, since selling it while on the quest is a complete waste. Other then that, you just need to make sure to only rely on one type of pet food, as well as probably not buying potions since you can't afford them anyway. Just try to only go as far as you can survive on one health bar on each run. I found myself AFKing a lot to heal in the start when I was too poor to keep using the inn, but that eventually changes.
[TIPS!]
--> Replace your pets.
Now, I didn't get a chance to try every pet, but I did find their lack of listed stats annoying. Generally, the later you find an enemy, the better pet it will be, sometimes. The poison snakes leave a weak poison ability, which makes them nice I guess, but once I noticed the ice scorpion has a chance to instantly kill an enemy, I basically couldn't replace him. I tried a skeleton, and I'm hatching a skeleton warrior who would need some leveling, but really, the instant kill is nice for when you can get him, if you play that long.
--> Know when to quit.
Don't push your lifebar too much. It's much better to give up pushing further one screen away from the generator of a level then to try to get to it, and die on the way back. Saving frequently is the key, keeping your experience gain consistent. Too many times did I think I could survive my way back only to get cornered when I least suspected it, usually resulting in me or my pet dieing.
--> When in doubt, use bugs to your advantage.
Okay, so most people don't like using bugs to get further, but there are two that will not only save you time, but make you able to take less damage.
First of all, the hatching is based off your computers clock. So you can save after you start hatching, and come back later in the day and it should be done. Or, you can just cheat all together and change your clocks time for a moment to get your egg hatched instantly. Kinda cheap, but waiting 2 hours can be annoying.
The biggest tip I can give is actually a rather large bug. When fighting enemies 1 on 1, you usually just trade shots until someone is dead, which results in a lot of damage. Most of the time you will be scared to fight more then one enemy, to not get wailed on too much, however, when you start fighting a new enemy, you instantly attack. Because of this, fighting enemies 2 at a time can actually prove quicker, and less damaging then fighting them 1 on 1. Once you have two enemies next to you, start clicking like a madman. If you click once to select, then again to attack on each enemy, alternating back and forth, you will attack as fast as you can click, killing people rather fast if they both stay alive long enough. This should help you much more later on in the game.
--> If something is too strong, be a wimp when killing it!
You never want your pets dieing, it's usually better just to reset and keep a frequent save routine because of this. If you are using a new pet, or your pet just seems to get killed by an aggressive type of monster for some reason, just use some cheap tactics. Firstly, you can freeze your pet in a safe area behind you when you go to fight the pesky monster. For me, it was those female slimes where I started doing this. I also approached them with a barrage of ranged attacks firsts. Save all of this for monsters you would otherwise get destroyed by. Starting with a fire attack to do damage, and a lightning attack to stun works great. If you alternate killing people with this, as well as shield smash stuns, you can usually kill strong things pretty reliably, while leveling up your pet safely too. Sometimes, having them hide while low on HP is a better way to heal them then with food anyway.
That about does it for general tips and such I can think about, I'll list some of the items an abilities in the next post, so you know what to expect, and what to wait for..