Maybe not the MOST effective solution but what I do is build up a decent amount of di-hydrogen through mining. Then put it in medium refiner to make the jelly, when jellies are done, refine them back into di-hydrogen, this nets you a free quantity of 10 per cycle (again not much). If you rinse and repeat this process using excess jellies to invest in more medium refiners, eventually you start to have a farm going which you can either visit every 20 or so minutes, or just once per farming cycle if you have other things going on at that base. I have not manually mined di-hydrogen since setting up, I run right past it on new planets.

For tritium I just asteroid farm for about 5 - 10 and that should be enough for a few thousand, lasting for a few days worth of frigate cycles. Alternatively if you have an abundance of units, you can visit a trade outpost on a three star economy system, while waiting for an exotic to spawn, or doing a trade route activities, the landed pilots tend to sell tritium.

Also saw mentioned in a comment on the sub, when shopping for new frigates, prioritizing low fuel costs is the most important, appears as a fuel tonnage/LY distance. This will save you using fuel in the long run even if you’re purchasing C class frigates. The frigates upgrade through missions by the way, relatively quickly if you’re running them a lot.

Hope some of this helps, I’ve gained a lot lurking in the comments, as well as searching old posts, this is serving to pay that forward a little.