Two religious denominations exist inside the island of Madagascar at the start of the game: Sunni and Fetishist. Antemoro is the only sunni nation within the island, which provides the player a larger pool of possible alliances with neighboring sunni powers. Converting to Fetishist via religious rebels after conquering neighboring Madagascans is possible, but only recommended for more experienced players. Fetishism will make an Alliance with 穆塔帕 effortless. Furthermore, Fetishism has bonuses that stack up better to Antemoran ideas (tolerance of heathens +2, and the Waaq cult gives a -2 unrest; both stack up properly to the -1 unrest in the nation's ideas).
The only option for an early alliance would be 萨卡拉瓦. The rest of the Madagascan nations usually rival you and seek alliances between themselves. After conquering Madagascar, the player can ally 阿居乌壤 or 穆塔帕 to strike at 基尔瓦, which is the only way for expansion outside the island.
When seeking larger allies later in the game, the safest strategy is to look for matching religious interests. If Sunni, the 奥斯曼 are prime candidates, which can provide both protection against any attacking power, and can prove useful in offensive wars equally. If Fetishist, however, alliances would more difficult. Although any player that managed to expand well and field a large army should find an alliance with any great power feasible.
Maintaining good relations with 基尔瓦 in the early game is recommended, as this will provide your provinces facing the Kilwan coast with ticking institution spread. The player should not hang back from developing those provinces further to accelerate the feudalism spread. Having loyal Nobility in those provinces is also advantageous, and will speed things up even further.
After conquering a gold province (preferably Kilwa), the player should develop that province to both increase the gold income and be able to embrace the Renaissance. One should also make sure make sure that feudalism is already present in that province, since otherwise one would be wasting monarch power in an already embraced institution.
Antemoran ideas stack up perfectly to the Humanist idea group, as both have +30% Improve relations modifiers, rendering any negative opinion fast decaying. Unrest will also become easily managable, as every province would have a combined -3 Unrest, among other bonuses that quell rebellions.
However, reforming from a tribal democracy requires the player to have completed either Administrative, Economic, or Innovative ideas. Hence, once could first attempt to reform the government by completing one of those idea groups, and later take Humanist as the third idea group.