Technically this might belong in the general discussion or Tactics section.
Impierial fist build is typically based around
Lysandar and some Assault terminators, preferably TH/SS
Tactical squads in rhinos with Flamers and either Las or Plasma cannons
the Fists are a typical SM Gunline army. you should be able to find some help in the article or tactics section
Chapter specific styles mean what units should you use to bring the feel of that army to the table.
Ultramarines: nothing special, balanced, Calgar
White scars: Bike captains, bike troops, Land speeders, Tac squads in rhinos
Salamanders: all flamer and melta weapons, Landraiders with assault terminators, Dreds with melta guns and flamers
Raven Guard: Lightining claws, Shrike, all Tac squads in transports, bikes, Land speeders, Assault squads
Crimson Fists: Pedro, Sternguard, Scouts as troops
All these list are from Codex: space marines showing the tactical flexability of the codex