Hi,
I'm in the same position as you as I am not a team member, but enjoy the freedom to 'turn up and drive' whenever I fancy.
Although workshops and tutorials may help you initially, I've found that driving in a race situation can be quite different than hotlapping. Often in a race it's best to take a few tenths off to preserve tyres, or minimize the risk of running wide and letting followers through.
For improving your outright pace I would recommend spending some time analysing WR spr's (get from lfsworld.com), perhaps learning a few setups tips etc.
However, as for online racing I don't think there's a better way to improve than just putting the laps in, with a focus on improving slowly and maturely (don't try and outdrive yoursefl). Sure, take some time to learn new tracks and setups offline, but practise is really unbeatable.
Also, in my opinion consistancy is very underrated. Don't go throwing away a good race in pursuit of pb's - it's a trap easy to fall into
good luck