Upvote:1
Appealing only makes sense if you are absolutely certain that the consulate did not process your application correctly. If you are 100% sure that, given the application and documents you submitted, that your visa should have been approved, then appealing can make sense. You should include a letter which explains all of the documents you submitted and how they demonstrate your circumstances.
If you were refused because some documents were missing, then appealing doesn't really make sense; you can and should just reapply. Remember that, even if you have had a refusal, each application is evaluated on its own merits. The same is true if you have had five applications approved. So, no matter how many Schengen visas you get, it is wise to take care with preparing them so as to avoid a refusal.