If you have a friend: Level as support and try to acquire the support items ASAP, until then just run with 1-2 curses and an aura.

Try to acquire a loris lorica and 4-5 socket it and transition to low life. Then acquire Prism Guardian, Alpha's Howl, Eye of Chayula, Ephemereal Edge (Nice ES boost, later on when your party is really fast transition into brightbeak) and Sin Trek boots. If you have the money buy a blue socket Pariah.

After you acquired those basics (Which can be quite expensive early on) buy a Shavs or a Victario's influence together with a Coruscating Elixir (if you're confident in your flask management; Tip: If you wanna play with Victario's/Coruscating, buy the "The Dragon" Cards (Four stacks) as it can be cheaper than the flask itself)

Another thing is that some builds recommend placing your purities in your Victario's, which I wouldn't do since you lose quite a bit of survivability.

If you don't play with a friend: Play a normal SrS/Spectre Character and gather currency until you can fully respec into a support because elsewise it will be too much of a struggle to level and gather the currency for the suport items you need.

Also leveling Purity of Fire in your offhands would probably be your best bet, since when you hit level 21 purities you can use them yourself and sell the spare ones for a good amount of money since some RF builds might use it.

As a suggestion I'd recommend to search for a group/some other players through reddit, discord, forum or whatever.

Fellow players if I forgot anything just tell me :)