Perhaps give a bit more information about your situation, for an example are you on a budget, which cards do you already have that is strong and stuff like that.
Since your level 20 atm i presume your probably on a budget so ill try to suggest something cheap.
Roots half deck 11 stars / 13 stars
The deck suggested here should be fine for a starter ELO deck and if you don't buy the most expensive cards you can get the deck for under 5k clintz. It should be able to get you beyond 1200 in ELO and 1300 if you got the skills and time.
Use Ratanah If you can afford ratanah and don't mind that she is ELO banned now and then else go with Miken Moose.
Use Dreen if your on a budget or think Lolly and Yookie is enough damage reduction for your deck.
Use Fuzz if you use Miken Moose in the roots deck. If you use Ratanah in the roots deck i would go with Onik but he cost a bit and if you are on a budget then both Keanew and Otakool are good 3 stars.
If you are not on a budget and are willing to use between 15-20k clintz on your first ELO deck you can make better ELO decks than suggested here.
Generally cheap and effective clans to play in ELO are
Junkz is good too but cards like Gil and Rowdy cost alot and you need them if you want a perfect junkz deck.
Hope some of this stuff might help.
Refer to my youtube channel
youtube.com/MEEP012 i have some deck vids you can try out
anyway i'm having a writers block or a deck block i look in the public presets and use some of the decks or get inspiration to make one
anyway thats all the advice i can give you