I can only give you advice on the middle game because that's where I performed best.

Turn every Iberian settlement into a city except Valencia. Use your most chivalrous general to pop-boom Valencia into a Citadel ASAP. You want DCG's as quickly as possible. Also try to get Militia Barracks, Sultan's Racing Tracks and Huge Walls near your front lines so you can train Urban Militia, Granadine Jinetes and Christian Guard, respectively.

Establish naval superiority in both the Atlantic and Western Mediterranean early on. Use your navy to execute quick siege landings on rich coastal cities like Rennes, Marseilles, Genoa and Naples. By taking them by surprise they will have no time to prepare a meaningful garrison. Use either Urban Militia or DCG to assault the settlement. Be sure to bring catapults or trebuchets with you.

In field battles, a combination of Desert Cavalry/Granadine Jinetes, Arab Cavalry/Christian Guard and Urban Militia/DCG performs very well against spearmen/xbow armies. Use your melee cavalry to chase/kill the xbowmen and your swordsmen to mop up the spearmen. Support them with javelin cavalry.

Avoid fighting cavalry armies in the open. Your spearmen don't have enough armour to withstand charging European knights. Force them to fight a bridge or gate battle where you can beat them in a standing melee.

Moorish missile troops are generally quite weak so I didn't train them. I did hire merc xbows occasionally though.

Since you'll be attacking a lot your reputation will sink to Very Untrustworthy very fast. However, still try to obtain a strong Eastern ally early on. They'll provide a convenient distraction and may even aid you in battle. Avoid fighting the Pope, lest you bring the wrath of all Catholics upon you.

If you played your cards right you should have a sizeable chunk of Western Europe by the time gunpowder arrives. By then nobody can stop you, especially with your Camel Gunners...