Here are some useful stats. which will serve you well if you can take the time to memorize them:

The probability of being dealt specific hold'em hands before the flop.

ny pair                         16.0/1

If you hold a pocket pair, you will flop a set just over 10% of the time (8.5/1).

If you have four parts of a flush after the flop, you will make it around 35% of the time if you stay to the river ( 2.86/1).

When set all-in

These stats are very important to commit to memory to help you calculate your pot odds when a player moves all-in pre-flop.

Higher pair vs. lower pair - The higher pair is about 82% to win or about a 4.5/1 favourite.

Pair vs. 2 higher cards - The pair is about 55% to win. If the higher cards are suited and connected, it brings it down to around 52% which is basically a coin flip either way.

Pair vs. 2 lower cards - The higher pair is about a 5/1 favourite.

Pair vs. a higher and lower card - The pair is about a 5/2 favourite. There's about a 30% chance of pairing the overcard.

2 higher cards vs. 2 lower cards - The two higher cards are about a 5/3 favourite.

2 unpaired cards vs. a higher and lower card - The high carded hand is about 58% to win, around 5% less if the middle cards are suited and connected.

Long shots

If you are hoping for a miracle flop then here are the odds against each one happening:

Flopping a flush                                                 118/1
Flopping 4 of a kind when holding pocket pair        407/1
Flopping a straight with 5-6                                 75.6/1
Flopping a straight with 5-7                                 101/1
Flopping a straight with 5-8                                 152/1
Flopping a straight with 5-9                                 305/1
Flopping a straight flush with 8-9 suited                4900/1
Flopping a royal flush with A-K suited                  19600/1