You want to get your other 2 characters up to level 50. Then pass your highest weapons over to your 2nd character and do your milestones. Then pass your highest weapons to your 3rd and do it again. The following week start on you highest character do milestones, then pass guns to your next highest and so on. Through out this you should get some better weapons which brings up the next guys power level so his armor drops higher and at some point guns. All dependent somewhat on rng but it works. If you only run guy you will not very much progress.

always do weekly and daily milestones and try a raid. Make sure you are in a clan to get clan engrams too https://www.bungie.net/en/ClanV2/Chat?groupId=2970652 or another WIN clan