Shoot for the knees/face, always. Suplex/Kick > Knife to death (if applicable).
Guns....
Striker (use regular shotty til you get it)
Semi-Auto Rifle (though use the BAR until you get it).
TMP (optional)
Standard Handgun
Broken Butterfly (and) Killer7
Red 9 is a great handgun, as is the Blacktail, but for professional, the primary function of the hand gun is to set up the Suplex. For that reason, I stick with the standard Handgun since it's cheap, and when fully upgraded does pop heads pretty consistently.
I am one of the few diehard fans of the Riot Shotgun, but I can't deny the strength of the Striker in Pro. Once you get it's exclusive, you will be hard pressed to use all of it's ammo before you need to reload, and speaking of reloading, it's a space saver too since you can fire your shotty up until you can refill it with all your surplus ammo.
I LOVE the BAR, but in pro, speed can be of the essence, and I still use the BAR, but most people will argue the SAR will make the difference in the clutch situations it is needed.
I used to ignore the TMP and sell the ammo, but I actually enjoy it as a weapon. It is completely unnecessary, so if you are going to forgo any weapon, this would be it. If you absolutely have to have the TMP, make sure you take the Striker with it since it allows for more room. A great alternative to having a Magnum for the first half of the game really.
I actually like having two Magnums. I only ever upgrade the damage on them and then fire one til empty, then switch to the other til it's empty. Then I buy each their ammo upgrades. If you take a Magnum (or both), you really don't need the TMP.
Those would be my suggestions for weapons.
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