If you lvl up your self whit collection quests I suggest you to take so many grey mobs ( of course so low lvl that they cant harm you meaning that your hp regen gives you more hp than they deal ) that you can take then then let them hit you so long that your defence / parry / block maxes you can go for a smoke while youre doing this or anything else but make sure that they cant kill you!!! about getting your combat/spellcasting skills up just join a group and get them up... so easy...
and it doesnt matter if the mobs are grey or green your skills will go up fast anyways...