There are several things you can do to help raise your dog's confidence level and make it more likely that your training program will be successful.
Avoid reinforcing fearful behaviour. Petting and talking soothingly to the dog or picking him up reinforces the dog for fearful behaviour. A hands-off approach where you state that everything is fine will send the message to your dog that there is nothing to fear.
No punishment - ever. There is never a reason for punishment in a situation where a dog is fearful. If a dog is frightened, she is in an emotional state, not a learning state. Physical or verbal correction will only convince her that there really is something to fear. Punishment may even bring out aggression if your dog feels threatened and vulnerable. Avoid any type of correction; it won't get you where you want to go.
Safety first. Keep the leash on at all times in public and make all the exits in your house escape-proof. Deny your dog access to the front door. for instance, if she is constantly looking to dash out the door or tends to panic during thunderstorms or with loud noises.
Exercise and mental stimulation. Dogs that lack confidence need exercise more than ever. Chasing a ball, hide-and-seek, learning tricks, agility, fly ball, going to the off-leash park or any of the various dog sports are all excellent ways for your dog to release her energy reserves and the tensions of the day.
Paying attention to providing the right environment for your dog and making sure that it is one in which she can learn to trust (because it is consistent and predictable) will put you on the road to helping your dog become more confident and enjoyable companion.