German immigration

I am looking for an expert in Schengen visas to provide consultation about my chances of getting one. I already have experience with Schengen visas. I previously applied and received an approved Schengen visa. My main purpose for this particular visit is tourism. I just want to make sure I'm doing everything right and that I have a good chance of getting the visa. I need someone who is confident in their ability to let me know what my chances are and how to improve them (because i have overstayed for 3 days unintentionally). This is a very important trip for me and I can't afford to not get the visa, so your advice is greatly appreciated.