I'd start in the Wiki, under Methodologies. There's a lot you can do before, during, and after the shave. You might be shaving against the grain, or not preparing your whiskers, or you could be having a reaction from your aftershave, since that's a sensitive area.
Welcome to B&B! We've had a lot of guys clear up their skin problems, including me. So read a lot, use the search, and hang in there.
I'd start first with proper prepping of the area prior to the shave. The only time I've had a straight give me razor burn is when it needed some touch up work done or I shaved a spot over and over and over and over.
Hello there! I use shavettes and DE's and used to have the same issues. I finally took the time to properly map the growth on my neck and made sure to be true to the growth when doing initial WTG passes. It has not happened since, but YMMV, as always.
Before you resort to products, double check your techniques. Anytime I get irritation it is because I rushed or kept pressing for BBS. Make sure you are using NO pressure, only the weight of the razor. That applies to DE's and straights. Definitely check out the Wiki that Vlad suggested.
Echoing the suggestion to map the growth and reduce the pressure. This helped me with the same area. Previously I was doing two N-S passes over my entire neck (I have never gone for BBS on my neck - I'm happy with CCS in that sensitive area especially as I have to button up and wear a tie 4 days a week).
At the suggestion of another friendly B&B poster I mapped the growth and now on the bottom portion of my neck do a true WTG (center to ear for me) for the first pass and a very light N-S for the second pass. No more trouble!