To begin playing the game you may mint your first character and receive a free 1-star weapon to go with it.
There are alternatives to simply minting four characters, as this might get you a set of different element characters and won't synergize with just one sword.
A common recommendation for starting players is to either purchase characters on the market so they can get four characters of the same element.
A better option assuming you have sufficient capital is purchasing leveled characters as experience is a resource that costs time to obtain.
Purchasing characters can be a good way to get a head start, but don't disregard the weapon.
Suggestions on weapon purchases can be found in their respective section in the Strategies and Guides group.
Minting a character is the cheapest way to get one, however the current state of the game incentivizes a mono-element team as having four characters of the same element can allow you to leverage just a single amazing sword.
If you are able to secure a good 4-star or 5-star sword of any particular element, it might be beneficial to try and obtain four characters of the same element so they can all share and use that one good sword.
Level milestones are the most important aspect in managing character experience.
Be sure to take note of when your characters are about to hit the next milestone, and if a character has crossed that threshold refrain from fighting with them before claiming their experience.
It is also recommended to batch experience claims to minimize gas fees spent on claiming, as each transaction incurs a fee.
More information on the experience table, and calculations can be found here: