Re: Is there a guide on when to enchance armor/clothes?
Doing the Deadbeat Dungeon is "cheating". There's free exp, cards and gold in there, but it's not a necessity.
Enhancing your equipment this early is not worth it. You do not have the money to support it this early in the game. Also, since you're a low level alchemist not many will buy from your shop at this stage. To increase the likelihood of selling items you need to set some of your characters to "manage shop". This way they will manage the shop while you're doing dungeons, and thereby increase the chances of selling items. The stats Cmd and Serv are those needed for the shop. The higher they are the better chance of selling items. Some characters are better than others at managing it. (As you progress you will be able to have more characters at a time managing the shop.)
Yes, the third sake costs 20k, but you cannot finish that quest before chapter 5 or 6. Check your quest log and it will tell you when the quest will fail. If it says it'll fail when you reach chapter 7, then you can easily keep saving gold till chapter 6 before doing it.
Sell all the treasures you can find to the church, do not enhance your equipment and in general do not use your gold on anything that early in the game. Your store won't really be effective till chapter 4+, and even that may be a bit early.
That said, if you're having a hard time this early in the game you're doing something wrong. Are you using the right characters for the right monsters? Some of your characters got elemental abilities that are very effective against specific types of monsters, while other attacks will do near nothing to them. If you use the right attacks/spells your characters can take down monsters 10-15 levels higher with relative ease.
And finally, do not ignore stickies. This thread here: viewtopic.php?f=11&t=102
answers a lot of your questions and should give you an easier time understanding the game.