Characters training to increase their level is not something that happens very often and should be a major event in the life of any adventurer.  I expect players to make an effort when it comes time to train.  A simple "I am going to go training"  will not cut it in this game folks.  Training can take up to 4 weeks per level of training and at 1500 GP per week per level this can add up very quickly.  The length of time a character has to train will be determined by how much effort and detail they put in to training related posts.  The more effort you take the shorter the training period, this reflects a characters attitude and commitment to the process.
  Good role playing in this instance will save your charcaters time and money, it is worthwhile!

Player Characters will need to:

1) Find someone who can train them (this needs to be role played in your private threads).
2) Explain what training they need.  Improve fitness (get more hit points), weapons training (for better to hit rolls), gain new proficiencies or specializations.  Learn non-weapon proficiencies, access new spells or improve other skills.
3) Then they need to make some posts explaining/describing the activities they undertake during training.  Think about what kind of training regime/roster they are likely to complete.

All this will be carried out in your solo threads.

For we clerics & religious types:  Do you need to find someone who serves the same god (which is at least more ideal, I'm sure) or is a cleric of some compatible faith enough?

Clerics can only be trained by other clerics who worship the same God.