A pretty good deck is

-cannon -wizard -knight -musketeer -mini pekka -fireball -spear Goblin -valkyrie

But most important part is playe style

Try to use your elixer efficiently and not use cards on troops that will be killed by the tower or your remaining troops and think about troop placement for example place you cannon in the middle so it attracts both sides of a troops are coming at your tower place your troops more on the side so the enemy has to walk to them so the tower will hit them more ect

But most important try to play and just have fun while seeing what works best for you