Been there!
1. Switch to 3/16" beverage line. The key word being "beverage". The walls of the tubing are thicker and the inside of the line is smoother. There is a difference.
2. A pic nic tap is more prone to foaming than a regular tap. You may have to back the pressure off some when serving. The same if you use the shorter beer lines. Not a big deal, but not quite a set and forget arrangement either.
3. Over carbed beer can cause foaming problems. You can bleed off pressure, but it takes longer than you might guess. Sometimes several days of pulling the pressure relief valve repeatedly. A tip off is when you have a lot of foam, but little carbonation remaining in the pour. It seems counter intuitive, but that is what can happen.
4. Keep the beer lines cool as well as the beer when possible.
If the hose is too long, you will need to apply too much pressure to the keg to get a decent flow rate at the tap. This will eventually result in the beer becoming overcarbed and you will find yourself back to square one.
Get your beer carbed to the desired level. I would suggest beer lines of six feet. This way, the lines are not so long as to be a nuisance, yet you can serve the beer at a moderate pressure. Up the pressure to the normal 12 psi or so for storing and bleed off some gas when serving. You will use a little more CO2 doing it this way, but no big deal. Keeping the keg at the lower serving pressure will reduce the carbonation level in the beer, but this happens fairly slowly and it's easy to return it to the proper level with an overnight pressure boost.
You'll get the hang of it soon enough and this will all become second nature to you. Do some trial and error stuff with what we've given you here and you will be on your way.