Learning this was so powerful that it changed my life for the better in ways that are hard to describe. You must earnestly not care one whit about public opinion and be ready to thumb your nose at it. I wish I had listened all those years ago when I first read this counsel but I don't think I was ready then because my road to self acceptance was not yet complete.
Passing is all well and good but it is overriden by confidence because unless you are absolutely flawless you won't pass for everyone. What you want instead is that quiet resolve that says you've arrived and are a whole and confident person. You may even pass perfectly right now but then have that lack of confidence conspire against you and have people detect there is something not quite right.
By all means, practice with the make up and the clothes but above all practice understanding who you are underneath first and then watch what happens.
Trans or not, this is universal. Be fierce; be yourself.