The thing that helps is to play with a group of friends. Just doing things solo really isn't efficient. I had the same problem since I usually play all games solo and do my own thing. I thought I'd never get to do the vault because that means making friends and sending out invites. Now I've got so many people on my friends list I am never alone now. People are always popping in and out of my mission and inviting me to run raid with them. And keep working on getting vanguard rank up and buy a piece of armor when you reach rank 3. You can easily earn vanguard marks doing strikes and the Daily events as well as weekly.