I've been slowly working on my first Tactical squad, and have now managed to get two more Marines done, including my graviton gun wielding specialist. I was going to go with a plasma gun, but the graviton gun just looks too cool not to use, plus my gaming group won't mind if I say it's a plasma gun.
After posting some of my pics on the Bolter and Chainsword forum, I had feedback that the Shrikes needed something to break the red and black up. I realised that a perfect way to do that would be to use squad markings and a chapter logo, just to bring some more life to the models. I originally painted the Tactical arrows on, but found that I could get better results using transfers. I've never really used these before, but after some searching around on Youtube, and buying some supplies, I was ready. I decided to use the Raptors transfer sheet from Forgeworld as the chapter symbol would work nicely. These are the first results, and I'm sort of OK with them. There's a few creases that I've yet to work out how to eliminate (advice would be great here!), and I've had to paint in a few gaps, but overall the effect works. Mircosol and Mircoset are your friends! I would recommend that you try transfers, even if you're a bit nervous, as they can save so much time and effort.