Before I became Muslim, I don't remember which parts of my body have been in contact with dog saliva, do I still have to do the washing with earth? Thanks
Actually there is some difference of opinion (different schools of fiqh differ on this topic)... basically anything (vessel, cloth, hand...) coming into contact with the saliva of a dog becomes impure and should be washed... see here and here.
On the other hand it is recommended to make Ghusl as one of the first actions when you become Muslim which also takes care of impurities. Allah knows best.
You do not need to wash your self even if a dog licks you, or comes close to you. If it comes close you do not have to run away like it is a three eyed monster. The prophet (Peace be upon Him) said that if it licks a utensil of eating or drinking, than we wash it seven times.
إِذَا شَرِبَ الْكَلْبُ فِي إِنَاءِ أَحَدِكُمْ فَلْيَغْسِلْهُ سَبْعًا
If a dog drinks from the utensil of anyone of you it is essential to wash it seven times.
After washing it seven times, rub it with dirt/earth once.
إِذَا وَلَغَ الْكَلْبُ فِي الإِنَاءِ فَاغْسِلُوهُ سَبْعَ مَرَّاتٍ وَعَفِّرُوهُ الثَّامِنَةَ فِي التُّرَابِ
When the dog licks the utensil, wash it seven times, and rub it with earth the eighth time