Space marine 750 competitive list, IDK wat 2 do!

Hey guys, firstly i think you need to know what i have:
HQ(s): regular captian, Vulkan He'stan and Marneus Calgar
Troops: 3 squads of tactical marines (1 with heavy bolter and flamer, 1 with ML and flamer and 1 with ML and plasma gun)
2 squads of scouts (1 sniper with ML and 1 regular with Heavy bolter)
Fast attack: Stormtalon (havent got new rules so not played it yet (sky hammer ML and assault cannons)
2 squads of assault marines (1 with 2 plasma pistols and Sgt. with power sword and combat sheild, 1 with 2 flamers)
Heavy support: 1 land raider crusader (with MM)
1 predator (autocannon and lascannons, with storm bolter and HK missile)
1 vindicator (with storm bolter and seige sheild)
elites: Terminators (regular storm bolter/power fist combo, sgt with a power sword)
1 dreadnaught (regular MM and storm bolter combo)

I've played several 750 point games and i haven't won a single game yet (i like bigger battles!) but the majority of people at the local GW store play tau or grey knights, with mass shooting armies (tau players) and buff lists for the grey knights. im not sure what to put in my list, but aggression, i learnt, is better due to my earlier battles me being conservative and sitting back shooting, seeing as i didnt want to get obliterated by the riptides =P

it would b gr8 to hear back from anyone, and with reasons and possible tactics i could use with the list. also, the board area is quite narrow (half size) and so flanking is very rare/minimal.

thanks again!