sorry for newbie question but how do i know which of these types of 'bartender sellable' mission reward items i should be selling as "junk" and which of them i should be saving for later? ( re: Engineering )
There are lists online, even apps that overlay the game to tell you what things are worth.
Personally I grab everything not nailed down.
Assets can be condensed so are rarely sold.
Goods; Power regulators, suit and weapon schematics, ionised gas and compressed liquified gas are worth keeping. All others generally get sold.
Data; Manufacturing Instructions are always needed, beyond that there's loads of types, if you figure out which mods you might be considering you should be able to work out which data you want to keep, though data is usually sparse enough to hold on to for considerable periods before storage becomes an issue.