Welcome back and what server are you on Kuinu? I know that on Trabia people shout for pts all the time in Ul'dah. What I would do in your position is just do that...shout for parties, make one up. Don't the members of your LS rank up other classes as well? maybe see if you can get into one of their pts.

The best thing I would do is what someone suggested earlier, that would be get ppl in groups and link the leves. This is done by having one person start the leve and 3 others touching the crystal afterwards and choosing to link the leve. This greatly improves SP gain. During your outing you should join as many behests as possible, as someone said earlier the Battlewardens spawn every 30 mins.

As for grinding, there are some spots that I like to grind either solo or preferably with a small pt (because its extremely boring if you're the only one). Around 20ish I like to take a pt of 4 or more to Nanawa Mines, there we grind on Coblyns. As a cnj you might be able to solo these with your nukes and healing yourself, but its easier and quicker with more people. A place I would suggest for a party around 28 is Copperbell mines, they are east of Camp Horizon. Here you will fight more Coblyns. Once you get to about 35 head to Camp Broken Water and fight the Doblyns there. Once you are 40 head towards the ferry docks in thanalan. Over there is a place called the Footfalls, around there are higher Dobs. I would suggest a 5+ party for this. Try and stay away from the Diremites, they are very strong. lol its a lot of Cobs and Dobs to fight but I find that grinding on these are efficient. I have noticed that ppl that are 45+ go to Coerthas and have Raptor grinding pts.

As for gil goes, not sure what to tell you. Ive made millions on just cutting down logs and turning them into lumber. Once you get to a certain rank you will not need to spend gil as much, because you are not ranking up as quickly and the need for new gear or weapons is not there. I also just sell most of the items I get from mobs. Hope this helps.