Specialist
Specialist is probably the most fragile out of the classes as it has the least health. Your mainly gonna want to stay at range because up close against anything like a heavy, you probably won't win. The specialist's guns do a lot of damage and some being able to one shot a heavy with a headshot. I recommend to start of with using a gun with a higher rate of fire until you feel more confident at sniping at range and then using a low rate of fire high damage rifle. There are some maps where the specialist really shines like Hoth or Crait because there are so many open people to snipe. Some guns do have a tiny bit of travel time so lead your shots where necessary. Whenever you take some damage while scoped in, unscope and check because 1 sniper shot can leave you at 1 shot to death. Ability wise the specialist has a shock grenade which won't get you a lot of kills but comes in useful if someone is chasing you as you can throw it at them and shock them allowing you to get away to a range where you have an advantage. Specialist also has infiltration which takes you of the radar and pulls out the ee-4 which is an incredibly strong weapon. The only problem with this is that although you have an incredibly powerful weapon and are of radar, you need to get close to use it and you don't have a lot of health. Use this when you see an opportunity to flank and take out a big group of enemies one by one or when you are already close to an enemy and you want a weapon to deal with that. For the last ability, I recommend the personal shield as it comes in handy a lot more than other abilities. This is pretty self explanatory but if you are getting shot, want to get out of a fight or need to run pass a place where you can get killed then use this. The default ability is a pair of binoculars where you can see where the entire enemy team is and although this sounds good, it has its problems. You can't have a weapon with the binoculars out and it doesn't always work. This is great when looking for people to snipe who are hidden and looking for good flank routes.