During the play through, Lester will give Franklin some assassination missions starting with 'The Hotel Assassination'. If you want the most money for each character, it is best to avoid starting these missions until the end of the story when you have the most money. I then recommend following How to Become a Billionaire in Story Mode by TheVoidstarTY

Heist #1: The Jewel Store Job

Pre-Heist Setup
Make a save before you start the mission, just in case anything goes wrong during.

Patrick McReary is required for this heist. To unlock him, you need to do 'Getaway Driver'. This is a random event at the Dollar Pills Pharmacy in Strawberry (Just around the corner from Franklin's (and his aunt Denise's) safehouse.) Get a four-seat car (Franklin's Buffalo will work) and drive up to the two men holding up the pharmacist. If they're not there, drive up and down the street or sleep in a bed to advance time and try again. When they are there, don't kill them, let them get in your car. Escape the cops and drop them off at their place. Make sure when escaping to not drive past the police station. I did and they thought I was a snitch so they got out of the car and left. Once you complete this random event, they will give you $1000 and unlock you Patrick McReary as a crew member.

Heist Setup
Approach: Option B
Crew: Karim Denz (Driver - 8% Cut), Patrick McReary (Gunman - 12% Cut), Rickie Lukens (Hacker - 4% Cut)

Heist Summary
Option B is the easier approach as you won't be distracted by crowd control. I don't believe Option A would loose you any money, but you may not have time to gather all the jewelry. Karim Denz is a good enough driver for this mission. He will not give you directions and will give you road bikes for riding along mud, but as long as you stay back and watch where they go, you will be absolutely fine. Patrick McReary is the better choice of gunman as he performs the same as Gustavo Mota (14% Cut), but costs 2% less. Norm Richards is a cheaper gunman (7% Cut), but he doesn't perform as well. If chosen, he will crash his bike and drop his money. You can drive over the money and pick it up, but overall you gain more money with Patrick McReary or Gustavo Mota. Rickie Lukens will give less time to steal the jewelry, but it is still very possible to steal all the jewelry. If you don't get them all, I would recommend loading the save I suggested to make before the mission.

Heist #2: The Merryweather Heist

Pre-Heist Setup
Make a save before you start the mission, just in case anything goes wrong during.

Heist Setup
Approach: Option A (Freighter) or Option B (Offshore)
Crew: There is no crew for this heist.

Heist Summary
No matter what way you do this heist, there is no reward.

Heist Reward

Heist #3: The Paleto Score

Pre-Heist Setup
Make a save before you start the mission, just in case anything goes wrong during.

If you didn't use Patrick McReary in the Jewel Store Job for whatever reason, Chef is the next best to use. Chef should unlock from a random text to Trevor. If you are missing him, just play as Trevor for a few minutes until he appears.

Heist Setup
Approach: There is only one approach for this heist.
Crew: Norm Richards (Gunman - 7% Cut)

Heist Summary

Originally posted by Ricardmanzilla:

OP, dont take mcreary at paleto bay, take norm richards. Yea I know he dies but in heist 5 you will get another 7% cut person, hugh welsh, that doesnt make a diference from norm. In conclusion if u take norm in paleto instead of mcreary and hugh in final heist you will get more money.

Thanks to Betasaur for confirming Ricardmanzilla's suggestion.

For this mission, you will only need to hire a gunman. If you pick Norm Richards, he will be pinned against a police car and a wall. You can pick up the money which will result in a higher take than if you had picked a better gunman. A factor in this heist is every time a crew member is shot in the back, you lose some money. You start with $8,016,020, so it may be possible to keep it above 8 million, but don't worry if you don't, this isn't big money compared to later on.

Heist Reward

Heist #4: The Bureau Raid

Pre-Heist Setup
Make a save before you start the mission, just in case anything goes wrong during.

Taliana Martinez is required for this heist. To unlock her, you need to do 'Crash Rescue'. This is a random event on the Great Ocean Highway around Mount Chilliad. Along the highway, you should find a car upside down in a ditch on fire. If not, drive up and down the highway until it appears. Walk up to it and Taliana should stand up from the wreckage. Lead her to a car and drive her to Sandy Shores. After this she will be a crew member.

Heist Setup
Approach: Option B (Roof Entry)
Crew: Rickie Lukens (Hacker - 4% Cut), Hugh Welsh (Gunman - 7% Cut), Taliana Martinez (Driver - 5% Cut)

Heist Summary
The Fire Crew approach would earn Franklin $60,000 more, however this approach would require using two gunman, loosing more money. In the Roof Entry approach, the hacker will direct you a little better, and be able to help visibility later in the mission, although these are fairly useless. Although Taliana Martinez is the cheapest driver, she is also the most skilled. In this mission, choosing Taliana will mean she brings an ambulance for the getaway vehicle to avoid a police chase. In this heist, Michael offers to give his cut to the crew, so only Franklin will gain money for you.

Heist Reward

Heist #5: The Big Score

Pre-Heist Setup
Make a save before you start the mission, just in case anything goes wrong during.

Heist Setup
Approach: Option B (Obvious)
Crew: Taliana Martinez (Driver #1 - Helicopter - 5% Cut), Karim Denz (Driver #2 - Train - 8% Cut), Daryl Johns (Gunman #1 - 6% Cut), Hugh Welsh (Gunman #2 - 7% Cut)

Heist Summary
This is it. The final heist. If done right, it can gain you up to 40 million for each character. Picking the subtle approach, although more fun in my opinion, would only gain you up to ≈35 million. Make sure Taliana Martinez is the first driver (helicopter), because if Karim Denz drives it, he will crash. The gunman do not matter at all in this heist, so pick the cheapest you have. At this point in the game, if following this guide, the cheapest you have should be Daryl Johns and Hugh Welsh.

Heist Reward
Thanks to Starsailor for the picture.