At this level range, you should be familiar with the concepts of crafting for items. The most important profession your first character (main character) should have is Beastmaster, unless you plan to make your first character as a support character.
This is also the time to start thinking about what end-game gears your character should have. In most cases, the wallet gears are the best you can find ingame! The helm and gloves in wallet gives you 3-sec shield against incoming damage (IMPORTANT).
Upgrading gears to +5 can be done cheaply with crimson gems, so you can save your purple chance gems for later upgrades (+6 - +12). Furthermore, you'll need Power of Heroes upgrade for those gears you get from caves and not the Wallet.
Start preparing a character who's sole purpose is to harvest purple items from caves - which can be traded with the NPC below auction house for 19 purple signs. Then, the purple signs will be used for reforging. This way, you'll end up with a character of about 10,000 gearscore, which is fairly decent.
Stockpile your level 55 experience potions, so you can jump from level 70, to a higher level than 71. This way, you skip the intermediate levels in which you'll experience much hardship from lack of available games that gives experience (you stop gaining experience from most activities at level 70).
Prepare for high-leveled purple books.
Prepare for Glory or Mirror items.
Build up purple signs for Level Increasing Gems (increases item level from 41 -> 51, or 61 -> 71, etc).