I mean, I want to get used to a specific deck, so I can develope all my skills (in case I had) with that particular cards. Too many changes with the deck (or with the clans) prevent me to take out the full potential of each card.
But I am not sure how to check that the bad results come for the weakness of the deck or for my lack of skills. Or, even, that the good results mean that the deck is good or just that I have had a lucky streak.
For example, the deck I'm trying now (a mono Pirana one) contains: Selma, Raeth, Andsom, Taljion, Tyd, Ulrich, Spcyee and Tula.
I'd recommend Vortex & Ulu Watu. Ulu Watu are good due to their +Power bonus. Vortex are nice too, plus if you lose a round you'll get back some Pillz, so much less risk if you try massive pilling for KO. Hope this helps
That deck you've listed is fine aside from spycee.
Spycee's problem is this:
He's an off switch for nasty abilities, but you're almost certainly going to take damage due to his pathetic 5 power.
Even if you pill high and win you only hit for 2, and, due to his 5 power, you probably overpilled and left your Opp in a strgoner position.
Spycee to Hawkins as soon as you can and that deck will be solid.
A good way to test your skills is this. Find your average number of fights to 1300e. If it's around 30-40 you're playing much better as a constant than if you grind there over 70 games on average, for example.
Once you have your average work on bringing it down, that way you know you're improving.
You can only use this 30 games thing if you don't play on mondays and tuesdays ;P since it takes a longer time to get to 1300 during these days
You check if a deck is good enough by simply playing with it. If you are losing too much, try to understand why you are losing: Pilling wrong, or if some card on your deck is your weak spot. You get the hang of how to build a deck with game experience, but everyone needs to address the weak spots on their decks every now and then.