Red dragons: Not recommended since Red dragons can only be found in two places in my opinion: Red dragon island in the Wilderness and Brimhaven dungeon and OSRS gold both aren't near a bank; Black dragons - Taverley is crowded everywhere I would not bother, so Zanaris is the best choice according to me.

Metal dragons - There's not much to talk about here and all Metal dragons reside in Brimhaven Dungeon (Mithril dragons being the only exception) They aren't difficult to kill and come with decent drop rates; Frost dragons - 85 Dungeoneering required so it's not a viable choice for you now unless you're looking to learn Dungeoneering. You can also earn money from Slayer but unless you're getting dragon tasks every day, I'm confident that you'll earn more money just taking out Dragons.

What Silv suggested are all great suggestions. When I was your level I tried Experiments. From 60 to 70 and took me about 3 days. It was boring since you won't gain anything other than experience, however.

It's a bit odd because I'm not sure what I was doing between 70 and 90. I'm sure I've performed certain tasks, but I haven't performed tasks like bosses who were rangy The Circus. Not to mention Cannon. If you don't have a problem with spending money, you can also Cannon Dagannoths and you also range them.

You could also Chin But I wouldn't suggest Chinning til at least 80plus. A trip to Yaks could be a good way to get experience. It's around 40k moment, most likely. But that might be pushing the envelope a bit. Since there are plenty of bots in the world. I haven't tried Fire Giants though. I've seen lots of users doing it whenever I'm asked to buy old school runescape gold play with them however. It must be fine.