Rachel
I strongly suggest that you do a search of previous posts for 'builders cleans'. It is probably one of the most widely asked/debated subjects on this forum.
Many people have contributed lots of very useful information over the years and they are unlikely to repeat themselves every time somebody asks the same question - because they have successful businesses to run!
The quick answer is that it will take more than letters to be successful in the world of buildes cleans
Good luck
Mick