i would like to know to to make an alliance or truce? i'm playing the PoM campaign and sandbox. i already press m for diplomacy, from there i dont know what to do next.

At the top of the game you're playing you will see a bird, in truth a dove, press that for diplomacy. I have only been able to make truce or war; I am not allowed to make allainces so that's all I know about diplomacy; it works. I haven't been attacked by those factions which left me free to take Macedonia, Illyria and Thrace; then I intend to turn toward Greece proper.
Good Luck on this great game.

Alliances are not allowed in the Phillip of Macedon scenario so the option will always be unavailable. But truces can be made with other factions as described above. make sure you have enough spare money though as you will be unable to make the truce without a decent amount of cash as defined by their intimidation level compared to how hostile they are to you.

ie. Higher hostility drives the price up and higher intimidation drives the price down. it is possible to get them to PAY YOU if they are not very hostile but very intimidated, but generally it will involve you paying them some money for peace.

In the sandbox you can make an alliance for a higher price. This will give you control of the faction and allow you to recruit in its cities. This has the added benefit of making the units slightly cheaper, have higher morale than normal mercenary units and the cities don't require a garrison.

here's a quick question related to this. is there any penalties for declaring war on someone you have a truce with? in my Philip campaign I made a truce Paeonia so I could focus on taking out the Illyrians. Now that I am done that I figure I want to do the Paeonians.

Thanks!

According to BLxz there is a price to be paid for violating a truce ...but I found that the cost was negligable
compared to the ease of having a truce and then coming back to wipe them out. I did so with Epirus ; they were tough and kept on attacking me, so I made a truce and took over the Western Odrisians before coming back to Epirus.

right on! thanks for the reply! :)

The price is indeed neglible compared to the benefits of a truce. But it affects all factions I believe, so continually making and breaking truces will stack up over time for every faction on the map.

But don't let that stop you. In my current game I've made a truce with the south and western factions and plan to expand as far east as I can. That will easily be half the game. Returning to break all those truces later won't be too bad.

But avoid alternating making a truce, then breaking it, then coming back and making another one, then breaking it. You will encounter high costs for garrisoning in your conquests later on.