When starting out the first thing you should concentrate on is both souls and planting.

SOULS:
Souls will increase the effectiveness of your Abode which will in turn increase your Cultivation Speed and the Speed at which you learn Manuals. It will also increase the Amount of recources you Gather which will mostly come in Handy when grinding Cores for money/spirit stones. They will also help with tribulations although that mostly helps in the End Game.

PLANTING:
Planting is the most important and for starters the only usefull Skill. It allows you to increase your "inherent" Atributes, being Qi Sense, Attunement; Root and Bone, Talent, Chance. In the beginning the most important Stat to increase is Qi Sense since it increases your Cultivation Speed but Having one plant to increase Talent is also smart since it increases your Manual learning rate.

When it comes to cultivation, until you reach "Comprehending Emotions" its more worth it to just max out the basic "Breathing Qi" since it it more effective.

Manuals are definitly a major part of the game, but you need to be carefull since sometimes the best technique is not the best to choose. When reaching certain Milestones in your Realm you unlock new Shop floors and with that new techniques but if you just unlocked the shop your Manual Learning Speed is likley not enough for the new techniques to outshine the previous ones so make sure that you can at least reach level 50 with the highest of your Manuals since at about that point a low Grade manual from the upper Floor is better than a low grade Manual from the lower Floor at level 100.

In your Abode you should concentrate on upgrading the Cultivation Room and sometimes the manual Pavilion. You should upgrade the Spirit Field when your Cultivation Speed and manual Learning Speed is sufficient.

When it comes ro Reincarnation it is actually pretty easy. Just put everything into Qi Sense. That is the most important and the other Stats can just be increased through panting if need be.