NINTHTJ

I used to swear by MechJeb - But found that the new SAS options (Prograde, Retrograde etc) were the only ones I was using on MechJeb anyway, so quickly stopped. The idea of "Less is More" is definitely the best thing I've discovered about rocket building, the majority of my failed ideas in KSP have been down to over-complication and excessively large first stages. Be happy with a effective, simple design. The only other piece of advice I think I could pass on, is sub-assemblies. I find I save myself a lot of time, effort and stress if I take a first stage that I have proven works, roughly guess the maximum payload weight it could carry into orbit/sub-orbit, and then re-apply it to any of my craft that need a first-stage and are within the approximate weight limit. Saves a hell of a lot of time.

CKAN! Lol, No seriously, Docking port alignment indicator/Kerbal Alarm Clock/Kerbal Engineer

0, I feel get too attached to my Kerbals and have to either rescue or revert whenever one gets into trouble - lol