Forming pacts with as many monster girls as possible is important for making
yourself stronger. You gain stats every time this is done, and forming pacts
with enough of one species of monster girl will give you access to a new skill.
Skills can be leveled up using skill points at Leannya's shop, which are
earned from forming bonds with monster girls. Each time you level up your
bond with one, you get one skill point. This means you can gain 3 skill points
from a monster girl each day.
You can also eat food to grow stronger at Leannya's shop. Foods increase your
stats permanently or temporarily, depending on the food. This, coupled with
the stats you gain from pacts, is extremely important for strengthening
Crops regrow every time you sleep when the sleep meter has reached 100.
This also refreshes monster girls so you can level up their bonds and get
more skill points. You can only gain a maximum of 3 bond levels with a girl
each day. It's important to sleep when you feel like it.
You can quickly travel between safe areas by holding up.
Changing the difficulty has no unique rewards, but it is challenging and
fun to try against bosses.
It takes more experience to level up a bond with a monster girl at every
level, up to a maximum of 60xp, which is a lot of waiting. Sex skill with
a monster girl species levels up slower each time you start sex with them
after having already leveled it up and stopped sex, so it may be beneficial
to have sex for a long time the first time, to make it easier to level your
bonds up later on. It can be noted that it's possible to use speed hack
function in CheatEngine to speed up the process, but this is up to you.
I would strongly recommend changing your default key bindings in the
options. The default key for the menu is "C" and you can move between tabs
with the left and right keys. You can also view a manual of all the
controls here. Be careful when changing key bindings, because some keys
are bound to specific program functions, such as the "V" key being bound
to screenshots. As far as I'm aware, these specific key bindings can't
be changed normally.
There are lots of secrets to be found that reward you with rare materials
and items. It's important to find these early on, if possible.