If you use Prochem use Pre-spray gold, and rinse with fibre and fabric rinse. If it's a bit mucky rinse with liquid woolsafe. Should not be problem but test any colours with solution before you you start. I had one today that would been a dye run waiting to happen, have not seen one like that in 10 years! Follow other advice but would add a really good vac before you start, good dwell on the pre-spray and brush in well before rinsing.
If you're still not that confident find a local chap on here to do it for you.