It's the same with your character. You cannot combat in the d'hide. To illustrate the severity of OSRS GP this, the statistics are similar to the following: wearing a ranged top or bottom and helm while meleeing will reduce your accuracy by 27 percent. Wearing the MAGE top, bottom and helm while you melee reduces your accuracy by a staggering 45%. Gloves and boots don't appear to have any effect however.
The last two points are why you should take advantage of the weaknesses in the creature. If you're facing Dark Beasts (which are the ones you're fighting now), and show a lack of range and you decide to engage in melee at them, you'll notice two things. One is that you can only hit.
Two , the magic damage actually increases due to your armour. (A alternative to this part is by wearing Hybrid gear, such as the Warpriest of Armadyl , which you can get by dropping Aviansies, and other creatures found in the GWD) It's also worth noting that you must get an Royal C'bow. Ammo is extremely cheap, costing less than 1 million dollars to make, and outhits CCB.
One last thing to remember: Utilize abilities as often as you are able to. If I'm casting Fire Surge on an glacor and use a magic ability do not use to make use of any arrows. Similar to arrows within range. For slayer tasks, you'd want to avoid ultimates, and focus on basics and thresholds, until you can use Guthix' Blessing to heal, or Berserk/Metamorphosis for cheap RuneScape gold some crazy damage.