There is really no way you can improve boat speed without relativity to another boat. You have gotten a lot of advice -- a lot of it may be right. But, I don't believe there is any magic place to set your main or jib. Everything is relative to the wind, the seas, your crew weight.., in other words, the old Three W's of Wind, Water and Weight.
That is where Speed Testing comes in.
In my latest book, "Sailing Drills:" there is a section on Speed Testing. Basically, you need at least two boats. One boat must stay the same no matter what -- you need a constant.
You should line up so that one boat does not affect the other's wind. Then sail for about two minutes and determine if one boat went faster and by how much, and one boat sailed higher and by how much.
Record that and do it over and over until you have established an average.

Now experiment with changes on one of the boats.., should be the one that is performing worse. You can try jib lead positions, mast rotation, mast rake, sheet tension, and even different styles of sailing.
But, be sure to try only one at a time and try it a number of times to get realistic data.
If the winds are fluky, forget about it -- try it on another day when the winds are pretty steady.
By the way, the data you would be gathering would be valuable ONLY for that wind, water and weight condition. Keep that in mind.

I know we spent close to a week here in Key Largo a number of years ago tuning the N6.0NA and came up with some pretty good numbers. Then folks started sailing with a more radical aft mast rake and our numbers went out the window. Sorry to say we never Speed Tested again after that to find the new magic numbers.

Also, the "loose nut on the tiller" could be a problem. Some folks are pinchers.., and others are footers. A good way to find out which you are is to try my "Eyes Closed Drill."
Simply go out sailing with another similar boat and get in what you think is your groove. Once there the Skipper closes his or her eyes and sails by feel. You are only eliminating of you senses -- you still have 4.., or maybe 5 in some cases, left. Use them. Feel the wind in your hair on your arms, feel the waves, the heeling of the boat, listen to the telltales tickle on the sail, etc.
After sailing for about 5 minutes, relate how you are doing with the other boat. One boat may be much higher (pincher) and the other much lower (footer).
In my Sailing Seminars I do this drill with the entire class and find it amazing the differences in helmsmanship.
Once you discover you are a natural footer, practice working on going higher. If you discover you are a pincher, practice driving off and getting more speed.

To give you exact place to put your jib settings, how must mast rake, how hard you sheet, etc. would be impossible to do in this armchair position we are all sitting in right now.
It takes work.

Generally, I will say this. The first day of every seminar I try to espy general sheeting of each boat. I would have to say that usually 90 to 100% of the students are not sheeting the main enough. The 90% is exact, and once in a while I will get a student that understands you need to sheet the main much harder than the jib. But, that is rare.
Of course, as mentioned in previous posts, you can't sheet in tight until you get flow across the boards and rudders. Once that flow is established, you can sheet the main very hard in most cases. Most folks err in the direction of losing gobs of power by not sheeting enough.
So, in essence, with your main not sheeted too tight, you are powering up (in 2nd gear), but not pointing very well. Once there is flow across the boards, you can sheet in and flatten out the sail (shift to high gear).

At any rate,
Good luck
Rick