Welcome back! Start using quests. A lot of quests give good exp rewards that will help you get decent foundation stats. Additionally quests will give you additional content access to OSRS gold thing, monsters and slayer masters. Using slayer, continue after quests. Personally when I came back I started out performing quests by looking about the old school wiki, in the sequence they had been published. I highly recommend watching Slayermusiq1's guides on YouTube, if you don't care about the story line, he helps get them through really quickly by telling you which dialog options to choose.
No problem! Would recommend you start with Waterfall quest, it is super simple and will give you a few strength and attack exp. Beyond that, there's a couple fairly easy quests that I would advise finishing. Lost town, dwarf cannon character spirit, fairytale part 1, grand shrub and shrub gnome village. Also complete all the f2p quests since they're very straightforward and fast, they will provide you with some fast exp and pursuit points. After those quests I would suggest aiming for fighter madness (for the dragon scimitar) and get as far as possible throughout the recipe for disaster quest, ultimately for barrows gloves.
Really, however, you can not go wrong regardless of what quest you do, you'll need to do them all someday as they're a necessity for something. Do the quests that give you farming expertise and get started doing herb conducts to make some cash. Doing Recipe for Disaster pursuit for access to Barrows Gloves is an essential for every accounts, and working towards it will help you train your skills all.
I continue with slayer, divided by as many quests as you can stand to do lol. Otherwise, I'd recommend going for 50 in most abilities and knocking out the easy and/or moderate achievement diaries. Trust me it's far better to get those done early to buy RS gold begin reaping the benefits whenever possible. Also note that is huge, don't buy bonds with gp anytime soon. It'll keep you broke for a long while. You start accumulating now, when you start bossing you won't have to use welfare equipment. That's most new players largest error, and that means you find a few lvl 100s using 50m+ lender and some that can't manage a bond.