TBH you've picked two of the worst clans to start with, for 2 reasons:
Firstly,
Piranas are a difficult clan to play with - even level 40+ players can struggle getting the best out of them.
Secondly, most of Nightmare's quality cards are expensive for a noob to buy. And even if you could afford them, they are falling behind IMO, with lower than average power and a lack of new abilities like Confidence, Revenge, Stop etc.
The best recommendation you will get is this:
Sell all the cards you do not need/want and buy
Montana. They have effective yet cheap cards. Then add
Hugo in there, and play in DTs to start with, so you pick up your 50c tournament bonus, plus the clintz for the battles and maybe a credit if you do quite well.
You should find a deck like this:
Hugo,
Spiaghi,
Prince Jr,
Filomena,
Oscar,
Murphy,
Veccio and
Rosa to be very effective and relatively easy to win with, with an 18 attack bonus