Hi community, I haven’t played DG for some time now, but I check the forum often, and since nothing has changed I'm addressing the last post (so far) on this other thread of mine, Once again, I'm a brazilian, and if english poorly written is something u want to avoid, well, this is a good time to close this window. Now, if u r not noob on this game, this post is not for u, here r the very basic of the game, things that u don't need to follow anymore, but new players should follow. And another thing, if u r a Pro player pls be constructive and give "pro tips" on this topic, I will edit the main post as good as I can.
Ok, so you are a Noob that wants to become better, what should u aim for, u may ask, lets see.
First, this game is not about killing, its about not dying. In case you didn't understand what I just said I'll bluntly said it again: Don't f*cking die. When u die u give ur enemy gold, XP and map control, and u want to avoid that.
So if losing is what u normally get, and u die a lot, play defensively now on, don't die, DONT DIE. How u can manage not dying? Well, Lvl.1-3 dont try to kill an opponent, don't try to push a tower, just farm ur XP and Gold, and if u THINK u may die, let them have the flag, hug a tower.
Now, a list of DG that normally wont hold a flag in a 1v1 situation (cataract, mainly, and low lvls discussion): Regulus, TB, weird Oak builds, weird QoT builds, Spit UB builds, Not healing Sedna builds, Hammer Rook build.
A list of DG that normaly will hold a flag in a 1v1 situation: Healing Sedna, Ooze HP stacked UB, Oak with monks, Erebus with monks, Tower Rook, QoT (but its to hard to be good with this DG, so, if u are a new player, QoT and any of her builds r on the first list, when u improve she will be on this second list).
A list to 1v1 goodness on holding flags: Sedna.
So, take this little piece of advice, if ur DG is on the first list, play EXTRA defensively, if ur on list 2 facing a list 2 or 3 DG, play EXTRA defensively, if u r playing a healing sedna, hold the freaking flag, if u cant hold a flag as healing sedna on a 1v1 situation, well, u really need to re-read a sedna guide or ask for advice on the forum.
Now, you are alive, its lvl.4-9, what should u do? Buy items, non-expensive ones, ie. the best items on this game. Godplate sux, Scalemail+Banded Armor ROX, Nimoth rox, Unbreakable boots ROX, the 1500 and the 1750 helm rox. Those r the BEST items on the game, get them. If u have the money buy lvl.1 currency or at least ask some1 on ur team (maybe the guy with more kills) to buy it for the team.
Now consumables u should buy and all the time have one on your inventory: Teleport Scrolls, ALL THE TIME. Scrolls will save u from a gank, will help your ally to be ganked, you will be able to defend a crippling tower and a portal that ur enemy is trying to capture. Always carry a TP scroll.
Another useful consumable is Flag Locks. But don't waste your money on this. On your lvl. of play only buy to secure ur portal and for capturing your enemy portal. BUT, don't bother to lock your enemy portal if you don't have at least catas, its almost worthless. And, capturing an enemy portal when u have giants and not locking them, well, thats just meaningless as well.
Another tip: if u die facing another DG on a 1v1 situation and its was a normal fight, ie, both with full health and mana, don't try to take him out again, unless u bought some new item or consumable, u will die again, and remember, DONT DIE.
After u understand this basic stuff, and know how to play with several DG, and know their builds by heart, read the topic I linked on the start of this post.
How do you start with a DG? Read a guide, copy it, EXACTLY the same, only change a guide build after u know how to play very well with the DG, if you are not good enough u wont know how to effectively change the build, and u will die more, DONT DIE.
Well, this is it, don’t die, copy builds, use TP scrolls and flag locks, improve your game, find friends to play together, get pro. DONT die, play defensively.
If u feel the urge to flame me, don’t, and dont die. 
For all my friend that still plays DG and is reading this post, all the best
Hope to play a game with u guys soon enough.
PRO TIPS FROM REPLIES:
use your spells on allies.
do not "waste" mana on creep waves, ofc its fine to do it if your team is pushing for a tower.
spells with utility are better than spells that just do damage. e.g. frost nova is better than fire nova
learn to use your spells at the right time. e.g. NEVER use oaks shield on someone who is on full hp. also NEVER do any overhealing with sedna.
always try and interrupt.
have map awareness, for example, check the minimap after u kill each creep.
know when to run and when to not fight
tell your team mates what you are doing at all times, if u are leaving them, out of mana, etc..
listen to your team mates. its very disappointing when a noob just doesnt feel like listening and loses the game for you.
use the ~ so you can see everyones HP at all times
keep clicking on where you want to go when you are running away. Lots of DG's will be distracted by damage and suddenly start attacking something when you really need to be running away.
and don't buy more than 1 level of currency, its not cost efficient (see the guides) and you will get pwnd by the other team as their stronger DG's or heavy creep waves crash into you.
In general a bunch of cheaper items are "better" than 1 really expensive item (as the cost/benefit ratio gets worse for more expensive items).
When fleeing while playing a generaltype ALWAYS press N (select all), so u dont put to safety only ur minions.