When you are on the world map, hold L2 (PS4) to bring up activities u can do to get rewards. Unlock your patrols, run the crucible challenges and you will get several challenges you can do every week to get luminous engrams (higher level to help u level up).
Do those every week per character. Find people to help you run the nightfall also. Goal is to get to 270 light lvl min so u can participate in the raid. Watch some vids on how to level up in destiny 2. Check all your gear for legendary mods (purple). Hold onto those and infuse other items into them for now.