How many types of cards should I have in a 40 card yugioh deck?

20 monsters -10 to 12 4 lv or less -3 or 4 lv 5 or 6 -rest lv 7 or more 10 spell 10 trap these are the common numbers

It depends on the Deck Type. (Example:) If you run a Synchro deck, then naturally you would not need many high-leveled monsters, as your synchros are high-leveled to start with :P. 20 monsters, 10 traps, and 10 spells is ok for a beginner, though u could vary the number.

It would depend entirely on the type of deck you run. A spellcaster deck, for example would run better with more spells, and certain deck builds are better off without traps. In general, it is usually wise to follow this format when building a deck: 20 monsters 10-12 spells 8-10 traps Please note that these are very rough numbers, but most people revolve around this structure when building a deck. It is advisable that under no circumstances should you have more than 20 monsters, unless it is a particular deck type that profits from doing so. Spells and traps should be more or less equal, though it is not unusual for a deck to run more of one category instead of the other. As for tribute summons, no one really does so nowadays since special summoning allows you to bring out monsters more quickly. But if you must include monsters that NEED to be tribute summoned, then have a max of 4-6 in a deck (depending on the number of monsters needed for tributes).

It varies with your deck and playing style. If you have ALOT of high level monsters, a good card to use is Masoleum of the Emperor. My deck is pretty basic. I have 21 monsters, 11 traps and 8 spells. Out of those 21 monsters, only 3 are above level 4. Everything else is level 4 and below. Other players have NO monsters above level 4, some have a alot. As I said, it varies on your deck and your playing style.