It is surprisingly easy. With a good manual (I have used Coffer's and the Ostermans') you can easily figure it out yourself. On the other hand a workshop is a great way to start. Some of the steps--pouring the collodion and developing the plate--are mechanical skills which need a bit of practice, so watching someone helps quite a bit.

Regarding image tone, there are many contributing factors but it is easy to get a warm tone so don't let that hold you back.