what I do to level bow fast is the following:

1-make a ton of wooden arrows, arrow damage has no incidence on the xp you get for archery skill
2-build 3 fine wood poles side by side, these will be your targets
3-shoot at poles until you run out of arrows
4-craft new arrows and fix the poles
5-repeat and rince

best tactic I found so far. enjoy your new skillups :-)