My suggestion, since there is so much information that can be given, is to watch some videos. Clinton Anderson is really good. I have his starting under saddle videos where he works with a blm mustang that had very limited interaction with humans. Even if starting under saddle isn't something you are thinking about right now, the videos show you how to round pen, catch and halter, desensitize, lunge for respect, and those type of things. Breaking it up over a long period of time instead of all in one day like Clinton does might really help. The vidoes are kinda expensive but I'm sure you can find clips of the things you need on youtube. Parelli is another good one that might help.