A New Job

Now, by this point in the game, you should be ~level 150 by the time you finish up Consigliere. If you've been putting all your point in energy (as you should), you'll find that supplementing with the "Bank Heist" job is quite tedious (which it is). However, at level 100, you'll unlock the "Settle a Beef... Permanently" job in the boss tier. While not quite as efficient as the Bank Heist job, it comes quite close and is much more convenient. So, from this point on, feel free to settle beefs in order to get your "filler" experience while working on mastering the underboss and boss tiers.

Now for underboss, you may find yourself lacking illegal transaction records, which is quite possibly the case. Simply spend a few levels between the settle a beef job and the steal bank records job. You'll gain quite a few levels this way pretty handily, and you'll be able to save your energy packs for robbing the electronics store. However, if you've been taking your time leveling up and have plenty of concealable cameras (you'll need a LOT for the Boss jobs), feel free to use an energy pack to collect documents.

Try not to level recklessly, stretch out your energy and master as many jobs as possible with each energy bar. I've said it before but it is worth repeating - each time you level, you'll need more exp to level again, but with less energy sitting around to do so. You should be able to finish off the Underboss by level 210 at the most. If you've been efficient, or have taken your time, you can easily be under level 200. It is important to get the Private Island (+5% exp) by around level 210, without it, any level past then becomes pretty tight!

Boss

You should shoot to finish off the "Underboss" tier by level 210 or 220. At this point, it is time to level off the boss Tier. If you have a private island, many of the jobs will be masterable quite easily and self-sufficient. The hardest (and longest) part about the Boss tier is collecting several hundred Blackmail Photos. However, if you've been using your energy packs to rob the electronics store, you should have plenty of cameras stocked and ready to go. Working this last tier will take a little bit longer. Even if you are using filler jobs to allow you to collect blackmail photos, this process may still take a day or two. If you diligently count energy and put all of your stat points into energy, you can probably master boss without waiting for any energy packs. I chose to wait since doing that is a bit tedious though; the point of playing a game is for entertainment, right?