The Saboteur is awesome, he just has a steeper learning curve than many kits.
With your current manifest I would suggest this build, which should see you through Bronze/ Silver just fine. You can set off savage tech bursts by using sabotage, then immediately firing a homing grenade. Use against groups of mooks to stagger and kill most of them. Any that are affected by sabotage will take a lot of extra damage from the combo due to tech vulnerability on sabotage. Note, this only works against organics, Geth and Atlases will be hacked but you can't set off a tech burst against them.
Against single targets sabotage then headshot with whatever weapon you've taken.
Equipment is just a suggestion, and you'll want to save most of the really good stuff for when you start playing Gold (cyclonics in particular). I find incendiary rounds really useful on the saboteur as it gives you the extra option to set off fire explosions, most usefully against Geth and bosses. Disruptor ammo would also work fine.
I suggested the Eviscerator above as it's one of your stronger weapon options at the moment, and you've got good shotgun mods. You'll ideally want a piercing mod before you take it to Gold with the saboteur though, as most of your damage will still have to come from your weapon. The phaeston would be ok once you have better assault rifle mods, and the Eagle would also be worth trying. I tend to use the Wraith, Lancer or Venom with him, and these are all worth a try once you get them. The krysae can also work quite well on him if you like that gun.
For tweaking the build, 5a and 5b on sabotage are both ok, you could try recharge speed if you prefer to take heavier weapons. As you don't have any grenade capacity gear you could take 5a on homing grenades if you keep finding yourself short. I go full weapon damage in passives as it makes very little difference to homing grenades, and realistically most of your damage will come from your weapons. I currently spec out of turret as I don't find it that useful compared to sabotage/ homing grenades. If you want to work it in, you could take it to 4 (with shock turret) for extra crowd control, and drop to 4 fitness. Or go for a no fitness build if you're feeling brave.