So what is the most profitable way to come across Gold in this game? Like should I just pick and sell everything I come across or how do you do it to maximize gold and get good items?
The MOST profitable way... Is to steal it and anything you want. Vendors refresh their (Non-unique item) stocks whenever you long rest so you can steal all their gold, rest, steal all their gold again etc...
Of course, if you don't want to do that, there is of courrse, picking up everything to sell.
Personally, I don't pick up everything. I only pick up things that have high value for their weight (Magical items and jewellery) because you eventually find so much stuff that you'll be swimming in gold.
My next question is what is the best party composition. My main is my Paladin - then I have a rogue, cleric and fighter and sent my mage back to camp ???
"Best" is generally unnecessary and would be technically be a lot of abusing of overpowered abilities and tactics which is not ideal for a new player.
Generally, anything will work and you can make allowances for various compositions to fit in your preferred companions (Even without using Withers to change their classes)
In terms of making things easier as a new player;
- Having a character with high Dexterity is good, ideally with proficiency in Sleight of Hand for to be able to open locks and disarm traps.
- Having at least 1 character to act as a "Tank" on the frontlines. Someone with high Strength and Constitution to take the brunt of the focus from enemies (And stand next to things to "Threaten" them so they receive an Attack of Opportunity if they try to move away, thus they are less likely to run after less durable allies) and is able to throw or shove enemies to keep them where you want them.
- Having at least 1 caster is often good. Casters eventually get access to potent area damage spells which will help massively in most combats where you will be able to damage and zone out multiple enemies.
- A Cleric or Druid is a useful addition to a party, because of being able to use the Cantrip "Guidance" to provide a bonus on any skill checks you do (You can find an amulet that grants anyone this ability fairly early on, but it's easier to simply have a character able to cast it, especially when you find more amulets that provide combat bonuses so you don't have to swap them constantly)
If you keep these things in mind, you shouldn't have too much issue while you get used to the game. At which point you can start experimenting with more varied compositions.