Welcome back! This is RuneScape, where there is no right or wrong answer to what to do next. A lot depends on how much time you have to play and if you're looking for quick things to do, or if you've got an hour or two at a time to dig deeper into things. I always recommend finding what you enjoy and do that, whether it is dividing your time between two or three skills that you like to get higher levels on, no-lifing one skill for a while, getting some quests done, or trying your hand at bossing.
Your RuneMetrics shows that you are in a clan. Does your clan have regular activities you can participate in?
If you are still stuck, there is a 'Guide for returning players' on the wiki:
The most exciting this about this game is you can go any direction you want! A common thing to do at the start is to pick a stat that seems cool and just start to train it. Look to the wiki for guides on training individual skills. You'll find eventually that you need certain quests complete or items to level your skill faster to 99. You'll often need other skills leveled to finish the quests. It's all tied together, so starting with one special skill can be your anchor.
Yes, as Mod Tren said a good clan can be so helpful in your leveling process. Did you know that most clans give you a 6% boost to all experience just by doing a little skilling in your clan area? It's a great deal and will certainly help you in your journey. It's called "capping" and you can ask your clan about it if you want that boost.