See also the "worrying" section in Marc Segar's Survival Guide. In particular, learning to laugh at yourself, and to recognise your mistake, apologise and just move on can save many a bad situation.
The single best way to reinforce self esteem is to know where to go to be safe from making mistakes that have ongoing consequences, and to know that you can get there. These can be places, behaviours, or frames of mind.
Having a reliable visualised understanding of the environment you are in that you can fall back on in times of distress can help a great deal to pacify overwhelming negative thoughts, and help you plan ways out of bad situations.
If your failures keep haunting you, knowing that you have learned as much as you can from them can help that stop.
Non-autistic people learn from experience this way anyway, so worrying excessively about possible future failure is probably overkill.
Faking self esteem can have its merits:
It means that you will be less of a target for social predators.
Being less of a target means your self esteem has more time to rebuild naturally.
A person who is supremely confident has no need to prove oneself and therefore has no need for ego. This is directly at odds with the idea that ego helps a great deal in the competition phase mentioned in the section "the art of self confidence".
A person who is supremely confident settles conflicts so that every party wins as much as possible and therefore has no need for aggression.
A person who is supremely confident has little to be scared of and therefore displays their more positive emotions rather than their negative ones.
There are also some thoughts about emotions in relation to maintaining one's self esteem.
It is necessary to let some negative emotions "radiate". If you don't permit yourself to do this sometimes, things can reach a boiling point and explode inappropriately.
Although autistic people seem to be incapable of reading the emotions of others, the emotions they express are VERY readable by others. The confusion others have in reading those emotions are in the fact that the emotions often don't make sense.
Fear and anger are emotions that are communicated across species, and between autistic and non autistic people. They are "reliable emotions".