You can hold down the mouse to repeatedly fire arrows.
The Archer has a maximum level of 100, you can continue to earn experience but it will not increase the level of the Archer.
You will earn exactly enough skill points to raise all your skills to max level, so don’t worry too much about min-maxing your point buying.
Recommended early skill point buys: Putting enough points in to get passive skills, especially attack speed, attack damage, critical chance, critical damage, fire damage and mana regen.
Reaching Archer level 25 and 50 will unlock the Rolling boulder spell and the Thunderstorm, respectively. These spells will eat up your mana, but are very handy for increasing DPS on chokepoints created by Ice arrows.
The Ninja will build traps that damage enemies for a limited amount of time after being spawned. Only spend when you need the DPS or have resources to burn, as they are not permanent.
In the resources window, the top row will automatically gain resources for you, but the land plots require active clicking to farm resources. I recommend only building Wood and Gold fields as they are the only resource that is required to increase resource gain per second, and Wood is required to build more arrows.
The combination of fire arrows and ice allow the Archer to create chokepoints where enemies are slowed down to a crawl while taking high damage from the fire on the ground. When both are in place, it is recommended to swap to regular arrows to conserve mana, then send another volley of fire and ice when they are about to expire.
Changing the current wave to a lower or much lower one allows you to passively gain resources to build the farm or purchase passive skills, at the cost of gaining much less experience per second.
Changing the wave number during the day will reset the wave spawn timer, allowing the possibility of infinite time between waves to allow for intensive farming of resources.