Alright first off i'll give some tips when your are getting a 99 skill. This should be good for people who are getting their first 99 skill. I'll post these tips as rules.
Rule number 1: Don't stop. Don't stop working on your skill your getting 99. One you waste about 20-30 minutes just switching to something else and 2. You won't make it to your 99 skill. If you keep changing to something else lets just say 10 times thats 200-300 minutes wasted. That could of been 93-95 which you could of achieved.
Rule Number 2: Be Patient. Take your time on getting a 99 skill. Playing 12 hours on just one skill isn't much fun. After a while you will get extremely bored. So i'd suggest just playing 3-4 hours a day. This way you won't get bored. You don't need to get a 99 skill in 2 weeks. If you happen to play 8-12 hours a day and just working on one skill, it gets really boring, and will increase your chances of quitting. Anther thing for patience. Don't set up daily goals. Just work on it and see how far you get.
Rule Number 3: Make it as fun as possible. You want to have fun while getting your 99 skill. If you truely don't like that skill. Then don't do it. Combat skills are always fun because theres so much to do. Another thing is choose a skill that you can do many different things with. Like i said combat skills are fun because theres so much to do. You can go pvp and train. Bounty hunter, clan wars, god wars, duelling arena, etc.
Rule Number 4: Don't look at your experience. If you look at your experience alot for your skill it seems slow, but if you wait and look at it every hour or so it'll seem pretty fast. Thank Cash 91 for this rule. He reminded me to add that.
ok hopefully these 4 rules will help you on achieving your 99 skill. Lets move on to skills.