Good material is questionable if you are looking for full-on books, but there are some interesting paragraphs in English if you read some of Stephen Turnbull's Osprey series (Crusader Castles of the Teutonic Knights, 1 and 2).
If you pass by the requirement for this to be in English, then the Livonian Rhymed Chronicles are an option, but I am unsure whether there is a translation into English that is accessible (there definitely is to both Latvian and Estonian) (there seems to be a translation into English from 1977 but I have no idea how easy to access it would be).
For a broad description (based on the above sources)... I think, firstly, the time period you have provided is too broad. I'm going to cut it into two (1200 to 1385 and 1385 to 1500, with the latter having a lot more to read, even in English) though that's by no means a very clever way of separating one from the other.
12th to 14th Centuries
From the 12th century onwards, the local Baltic tribes were in (military) contact with the German peoples. Firstly, this can be said to have boosted the development of military tactics -- especially advanced weaponry such as crossbows and types of fortifications. The masonry fortifications built by the Germans were a new style in the Baltic lands (though this isn't to mean that stone had not been used before -- rather, it is the question of using mortar to link the stonework and to create a stronger platform which was new). This also meant that the Germans/Swedes/Danes brought with them a newer concept of sieges and engineering skills.
The local people did not have knowledge of the crossbow until they managed to imprison some Germans (or German mercenaries -- cannot remember) after a siege who they pressured into teaching them the art of crossbow manufacture and use. This took place in the latter part of the 13th century. The art of the siege equipment had been learned first by the Baltic peoples (first as in before small arms), and from Mr Turnbull it seemed as if the Lithuanian dukes were very keen on developing the art of siegecraft in their lands. This would partially be due to the large number of German castles springing up both to the south and north of the Lithuanian lands.
For fighting styles, raids (and counter-raids) were the most common -- raids for cattle and slaves that is. Conquest of lands does not seem to have been a primary objective while there are records of Lithuanian raids into Central/Northern Livonia well into the 13th century when those lands were owned by the Order. It should also be noted that due to the dense woodland nature of these lands, ambushes were common such as the one at Sauga in 1236 where the Sword Brethern were annihilated while crossing a river (though the full blame for that defeat should more probably lie with the 'conscripted' German crusaders who supposedly did not heed the caution of the brothers).
14th to 16th Centuries
From the time of the Lithuanian-Polish union of kings (late 14th century), the Lithuanian army would have started to take on Polish elements (and vice versa). Looking into the Tannenberg campaign of 1410 would therefore be a very good thing for that time and, in general, to see the sort of tactics the people of Poland/Lithuania had evolved to successfully fight against a heavily armoured cavalry force. However, Lithuanian armies would have mostly consisted of light cavalry armed with spears while Poland supplied some heavy cavalry and heavier infantry.
There is a lot more information available on this latter period, so I'd suggest looking at such campaigns as took place between the Order and Lithuania-Poland (including the above-mentioned Grunwald / Tannenberg).
This is overall a very brief overview and already it is quite lengthy. There are entire phrases used above which could probably be expanded by books, but I hope that this can prove a good starting point for any exploration you wish to make into these lands. Some good modern overviews of the Western conquest of the Northern Baltics has been written in Swedish (Jonathan Lindström), but I am unsure how much of it has been translated into English. I am unaware of equal works that deal with the Lithuanian side though there is probably an extensive literature in Latvian and Lithuania.