Glad you have some 4* already, after a week that’s good going !
But you’re probably better focusing on a solid 3* team 1st - the ascension materials to take your 4* to the max will be your limiting factor
If you’re spending gems on hero pulls, the Avalon event starts tomorrow and has some of the best special event heros e.g. guinevere. These are limited time offer heros
You will find lots of advice on here if you search for it - plus you should join an alliance which will help you along.
I have openings in Guardians Reborn, other good training alliances are available 