Sarcasticgamer wrote an expansive review of Metal Gear Online that includes tips and tactics for some of the gametypes and an in-depth review of the game itself.
From the review: "Aside from physical appearance, your MGO character has 4 'skill points' at their disposal which can be filled with a variety of different special abilities. These can be anything from advanced weapons handling (where you will suffer less recoil and can reload faster), improved running speed, close quarters combat upgrades (chokeholds, etc) or even the ability to see landmines where others can't.
The strategy lies in picking skills to fit your gameplay style: if you're an all-out gung-ho fighter, give yourself some agility and an assault rifle skill, or if you fancy hanging back equip yourself with some sniper rifle expertise and a good throwing arm for some long-distance grenade barrages. Either way, the scope for adjusting your attacking style is pretty large, and these skills can be changed at anytime if you want to change how you play." -