Crackdown 3: Campaign

Getting any skill to level 5 will likely come with natural play time. Focusing on actions that boost any particular skill will get it leveled up, and the first three levels come pretty easily. It’s likely your gun handling skill will be the first to hit level 5 if you’re playing the game naturally, but some may want to focus a lot on driving or agility instead, which each have plenty of opportunities to level up quickly. I think your best bet is to just play it as it comes though, and you’ll have several skills above or near level 5 by the time the credits roll anyway.