The best decks focus around an archetype - a group of cards with similar names and mechanics who support each other. Decks focusing around an attribute or type aren’t very good. Neither are most decks with multiple archetypes, though some mesh well. There are many different archetypes, and each has many different styles of being used. For example, the main strategy of a Monarch deck is to keep tribute summoning more powerful monsters, and to activate effects while doing so, but that is only one of the archetypes. There are many more to discover.
LV 1-4: Around 12 LV 5-6: Around 2 LV 7s and higher: Never more than 2, depending on the deck. Some decks can and need to be all high-level monsters. These decks are usually able to summon their monsters some other way than tributing. For example, decks like Malefics and Infernoids can special summon all of their high level monsters. For many other decks, especially ones that rely on the extra deck, it is not recommended to include any high level monsters that you can’t special summon.
If you’re running a high monster count, such as in Dragon Rulers or Mermails, 3-6 traps should be enough. Some decks run no traps, and do fine. A good choice for a deck that relies solely on monsters would be Royal Decree.
Remember to never use forbidden cards in tournaments. You could use them when dueling with a friend but he/she might not accept the offer.
