Don't be discouraged by "bad days". We all have them. The decision to stay and accept is made more than once by most of us.
If you cannot yet be supportive, at the very least, dont be hurtful. Remember that words can cut deeply and they cannot be taken back.
Always keep in mind why it is you love your partner. The soul doesn't change upon transition.
Try to respect your partner's feelings as well as your own. This situation is likely as confusing and frightening to your lover as it is to you.
Don't buy into stereotypes. Do the research, LEARN THE FACTS!
Letting questions and concerns fester inside is not healthy for you or your relationship. Talk about things and learn to compromise.
People are not perfect. You will both make mistakes. Learn from them as they happen.
Shock, anger, fear and confusion are all normal reactions. Don't beat yourself up for them....but don't take refuge in them either.
Don't delude yourself that this will go away if your partner just loves you enough. It doesn't work that way. They cannot control it for you or anyone else.
Transgenderism is not a sickness and cannot be "cured". Seeking psychiatric counseling is a good thing for help in dealing with issues, but don't expect the impossible.
There is no shame in loving a transgendered person. You are not alone in what you are feeling. Find support....it's out there.