Here is how to calculate your equity on the fly without using your phone (To make it easier we are gonna pretend you spooked your opponents cards when they were being dealt and we know his exact hand):
step 1. Count your outs, we have a flush draw on a board of 5h 10h Ad against our opponents top pair (Ac 4s), we have 9 hearts left to complete our flush.
Step 2. We have 9 good cards with 44 cards remaining. 9 goes into 44 just under 5 times, 5 goes into a hundred 20 times so we have a little under 20% equity to hit a our hand with the next card.
To convert that to fractional we can say 20 goes into a hundred 5 times so we have a 1 in 5 chance to get there and so this is 4/1 (note its not 5/1 because the 1 is part of the fraction, which is a common mistake for people to make). If we are going to get all our money in now (either because we believe he may fold his top pair certain % of the time or he has bet all his stack and we are trying to figure out if its the right price). Then we can simply double the 20% minus a little bit because 9 doesn't quite go into 44 5 times so it something under 40%
The quick cheat: we have 9 outs so we can simply times it by 2 to get the % of times it hit on the next street, 18% to make our flush OTT and simply double it to see for the river 36%, well you may ask what is 36% as a fraction? well how many times does 36 go into a buck? a little under 3 times id say (36 x 3 = 108) so you have a little under 2/1 chance.
Pot odds: same hand as above to keep it simples. the pot is 122 he throws in his last 65 do we call? well 122 and 65 make 187, 187 divided by 65 (its 65 for us to win 187 incase you're getting lost) is ummm. 65 uh 130 umm 195 so it goes in a little less than 3 times, so you are getting a little bit worse than 2 to 1, now pot odds are 36 divided by a hundred also a little worse than 2/1. seems about breakish on the old even, go on then I call!!!
Reverse implied odds. If you play against certain guys you will notice they almost always have the nut flush when it gets to showdown and all the money is in the middle when another dude (almost always a weaker player) also has a flush. This is one example of reverse implied odds. suited connectors are good hands if your good at letting them go when you recognise you're beat. Avoiding gutters that are not to the nuts is another example of reverse implied odds. chasing draws in multiway pots when your draw is not to the nuts and you could easily be against a draw and a made hand is another bad idea born of the principles of "reverse implied odds"
Stack sizes: Know your opponents stack size when facing a bet or when you are contemplating the size of a bet or even if you should bet at all. If he doesn't have much left compared to the pot size is he ever going to fold might be a question you want to ask yourself, You may ask yourself "if I bet now am I committed here because there is not much money behind? If effective stacks are very deep (600bb for example) and you are oop in the sb against a good player, you may ask yourself "should i 3bet my QQ from the sb here and get into a position against this guy where I could be playing an enormous pot? or on the flip side you are only 35bb effective you may just be asking yourself the best way to get all the money in the middle come what may.
A lot of things you will learn yourself as situations arise and you reflect on them, if you know the basics of calculating pot odds/equity/stack size then finding ways to figure out peoples likely holdings is all that is left.
If you play like a nit in your 1/2 game you don't have to understand too much at all beyond what is considered the basics, once you become an expert poker player (if you can't find a bigger game) it will become apparent its best to be a total nit in that 1/2 game