I don't have a lot to add to what has already been said other than PLEASE make sure that your airway is evaluated BEFORE any orthodontics are performed. PLEASE DO NOT just arbitrarily retract teeth to close gaps, this type of treatment could lead to disastrous results for your overall heal...
Invisalign or braces are recommended for a short time to retreat relapsed teeth,however after your treatment a fixed permanent retainer is recommended so your teeth do not shift again.
If teeth are misaligned,or too far erupted then it is best to move them into proper arch form before veneers are done. This will result in less tooth structure being removed when veneers are prepared.