Without pretending to have more expertise than I really do, there are areas of the law that certainly do provide more cash clients. Impaired is the classic example. There are definitely lawyers who specialize in this, and it's its own niche. The lawyers who build a practice in this area do very well. Other areas of law are harder to specialize in. While a few lawyers are known for a few things, it's hard to market yourself as a "sex crime" lawyer, and do so well enough that when some random member of the public is charged with molesting the nanny you're the lawyer he thinks of to the exclusion of other lawyers.
I suppose you can spend some time thinking of ways to market yourself. Maybe you'll think of something original. But the bottom line issue is this. Your practice is you. If you open a coffee shop, you can "cater" to a particular clientele based on your products, your atmosphere, the sort of experience you offer, etc. In a legal practice, it's just you. You're the entire product. So how are you going to cater yourself to a particular kind of business? You quickly realize the same thing many other lawyers have realized. That when we're talking about a client who has money and options, you don't have any realistic way to compete with more experienced, more established lawyers who have better reputations than yours. Ask yourself - if you were faced with a serious criminal charge, and you had the money to exercise a fair amount of choice, would you hire you? Hell, would you even hire me? Wouldn't you want someone with 20 years of experience?
Realistically, you start off taking what you can get, and when you do it really well you get opportunities to do more. Some client that you've served well on petty stuff gets charged with something serious. Some senior lawyer sees that you're doing a good job and invites you second chair a jury trial, or asks you to represent a co-accused on a major case. Opportunities come. But is there a clever way to short-circuit all of that, and to set out fresh on the market and somehow convince clients who have money and choice that you're the lawyer for them, despite the fact that you're so obviously green? Maybe. But if there is a way to do that, I don't know what it is.