Here's a few tips that may help youn while your training your fletching skill.

1. One way to get alot of fast fletching XP is through the miscellania manage thy kingdom, set your citizens to cutting maple logs, and just cut and drop the bows, you can get alot of hassle free fletching XP by doing this

2. Another way to get alot of fletching, magic, crafting and runecrafting XP, is to buy magic logs, set your miscellania to picking flax for you. All you do then is spin the flax and fletch the longbows, craft the nature runes and high alk the bows, this is also a decent profit too. and to top it off when you get 99 in fletching or magic, you can pass this xp to other people who want the xp and have them do the work for you, this helps speed up the progress, as well as helping someone else get XP.