Disclamer : This will not instantly up you archery skills becaus this requares practice.

Aiming: While in a pvp match or fighting mobs; you will want to aim and shoot your target quickly. Here are some tricks 
                
               1. When your enamy is far away try aiming up by 2 blocks and you might just hit the target.
               
               2. If you take cover and are away from any melee damage from you enemy, you will have more time to aim.

Enchanting: When you enchant your bow there is a huge chance that you get a bad enchantment and here is a trick

                    Step 1.  Make multiple bows.
 
                    Step 2. Enchant all your bows.
                     
                    Step 3. Fuse your bows with an anvil.

                    Step 4. Retry if you don't get good enchants.

Client side stuff : As a new archer it is good to have some client side benifits such as

                               1. Texturepacks
                               2. A Fitting FOV setting
                               3  Mods like Zans MiniMap


Your home base: as an archer or Sniper you want your base to be high up so you can get the best of range
                                
                                Step 1. Make a brewing room for potions
                                Step 2. Make a sniper tower thing that you can use to snipe enemy's
                                Step 3. Make sure only trusted people come to your house 
                                Step 4. Have a huge arrow storage