Red dragons - Not really recommended as OSRS GP Red dragons are only found in two places if I'm not mistaken: Red dragon island in the Wilderness and Brimhaven dungeon and both are quite far from a bank and black dragons. Taverley is packed everywhere, I would not bother, so Zanaris is the best option according to me.

Metal dragons – Not much to add here, all Metal dragons are located in the Brimhaven Dungeon (Mithril dragons being the only exception) They aren't difficult to kill. They also drop decent drop rates; Frost dragons - 85 Dungeoneering is required, so it's not an option right now unless you feel like training Dungeoneering. There is also the possibility to earn money through Slayer but unless you get daily tasks from Dragons, I'm fairly certain you'll earn more money just killing Dragons.

What Silv has said is all pretty excellent suggestions. When I was at your level I did Experiments. From 60 to 70 and it took me only like 3 days. It was boring because it's not a great way to gain anything beyond experience.

It's kind of odd since I'm unable to remember what I was doing between 70 and 90. I know I have Chinned various jobs, but also performed tasks like bosses who were rangy, the Circus. In addition, I have used Cannon. If you're not worried with spending money, you could even Cannon Dagannoths, while you range them too.

It is also possible to Chin or Chin, but I would not old school runescape buy gold recommend Chinning until you are at least around 80 years old. Going to Yaks could be a good way to get experience. The best is around 40k currently. But it's possible to push it a bit. Since there are plenty of bots in the world. I've never tried Fire Giants though. I've seen many users doing it every time I had a task of these. So it must be alright.