Okay.. I've completed the story 4 times so I can test my theory and it's proven true so I'll share what I know and what I did and did not do here.
This is how rich I am after "The Big Score" and Lester missions, and this is the core rules you need to remember..
1. Have Pen and Paper at all time. Without this, you're getting nowhere.
2. Patient. Can you handle Save and Re-Load 100 of times? If not, don't read any further.
3. DO NOT do any Lester's assasaination except the "Hotel" mission(compulsary) until you have complete the main story line "The Third Way"
..and the most important rule of all!!!
Every LCN Stocks move according to the story mission and events including "?" Strangers/Freaks event so what this mean is you need to save BEFORE you do anything!
- Write down the initial value before engage in event/mission
- After complete the event/mission, check and compare and find the most profitable stock
- Re-load the save and dump everything you have on it
- Go ahead and start the event/mission. Complete it and sell that said stock for profit
I did this for every event/mission from start til the end before engaging in Lester's mission and I have about $462 Million as you can see.
At the beginning the profit margin is very little but remember, "Patient" is the key.
- Save and reload if you not satisfy with the margin.
- Use all 15 save slots and write down which is which for easy to navigate and re-load
1. Collect all 12 Hidden Packages ($130k) as soon as you can or just using the glitch switch if you want to cheat. Youtube video guide below (not me by the way)
2. Invest some of your budget to "Vangelico" after the first "Jewel Heist" It will rise back up to around 70%-75% some time later then sell it
3. Upon complete "Nervous Ron" mission DO NOT buy "McKenzie Field Hanger" Keep your money!
4. While roaming around, DO NOT skip any random events. Rich kid with the bike stolen will net you $100k for free. Sell it straight away, it won't go up any further.
5. Completing "The Ballad Of Rocco" mission will make you a Producer. Invest in "RickardsMajestic" BUT! Sell it right BEFORE the "Melt Down" mission
These are stocks that has really low value early but will worth millions in the end
2. One of these fastfood franchise CluckinBell, TacoBomb, BurgerShot, Up-n-Atom (Invest in the lowest value)
3. MazeBank (The fall of Deposit Union make this stock untouchable)
4. Bilkinton (This stock net me $52m in the end)
Note* I do not recommend blowing up rival company expecting your stock would rise because it's very unreliable and in fact I never did any of that
Note* BAWSAQ will work once GTAO is launched. Right now BAWSAQ is scripted. All the number you see is placebo
Note* For people who can't be bother reloading the save for whatever reason, just keep Lester Missions after you complete the main story and you should make millions as well. Put it in perspective, you should have at least $45 - $50 millions after the last heist before doing Lester Missions
That's it! I hope this will help you guys achieve the BIllionaire status