What do I do when I finish the tree?
Since finishing a tree is always inevitable, here's some things to do when you finish the tree.
--> Solution 1 <-- Do your language backwards. This is most commonly referred to as the 'reverse tree'. I mean by this, if you learned Spanish, do English for Spanish speakers. It gives you a better understanding of translations, and can make doing both trees easier to do! Plus, you can see how the other tree is formatted.
--> Solution 2 <-- Start another language! This is called 'bridging trees'. Begin a language similar to the original one so that you can still strengthen original skills! Be sure to keep all trees as golden as possible. You can check out my 'How to do two languages' here: https://www.duolingo.com/comment/25360197
Thanks to InuzukaShino- --> Solution 3 <-- Focus on what you need to learn. If you want, switch to another language forum and do their 'tree' on the same language. Make sure you know all parts of the language before moving on.
--> Solution 4 <-- Do activities in your language. If you can, find a pen pal who is a native speaker and send them emails or letters in their language. Listen to songs or radio stations in your language. Find a language teacher to better explain your understanding of the grammar, vocabulary, and dialect.
There are the 2 solutions I've heard of, but I would love more suggestions from you guys! :))
I would suggest the following:
Check if you missed something in the learning tree
If you are still unsure about one or more topics or vocab areas, recap them till you learned them well. Doing this, you may reach level 25, but it is not necessary: If you know all tree content at an earlier level, it is ok, I would suggest you to go the next step, because it is wasting time trying to reach lvl 25 then (see my note to another answer below).
Clear up your goals
Ask yourself about why you learn a new language and what duolingo can do for you. Duolingo can give you a peek into a language, but not more. In case you really want to communicate and speak in a foreign language, you will need other or additional ressources:
Perhaps find a good textbook with good grammar explanations (you will master it quickly because you will already know most of the vocabs, so that you can focus on grammar and some new vocabs)
try out podcasts like the (language)pod101.com series
search for a language exchange partner to get used to speak (it is a certain ability which has to be trained.)
search for texts and books in the desired language which meet your interests and try to read, understand and translate them
watch clips and movies in the desired language with or without subtitles or watch clips and movies in a language which you understand well but with subtitles in the desired language
watch music clips in the desired language, try to understand, what they sing and - if you want and have fun with it - sing the songs by yourself in the desired language! :-)
Search for radio programs in the desired language with topics you are interested in, listen to them as often as you can and try to understand as much as you can
Write a diary in the desired language. This will develop your ability to express yourself.
Write small essays about topics, you are interested in. Give them to a native speaker and/or talk about these topics
Find native speakers as email friends and write them, perhaps visit them sometimes (or try to find native speakers in your town)
search for forums in the desired language (not neseccarily language forums), which meet your interests and try talk with native speakers about interesting topics in the desired language.
perhaps find a language teacher to learn more quickly. Native speakers are often not so good in explaining grammar and specials of their own language.
do this regularily, if you can every day and as often as you can. You do not need to do all of this every day, but try to do some of them at every single day for a while
Just immerse yourself into the desired language as good as you can!
Good luck! :-)
Please please please please start reading/listening-to native material.
Translation is a decent way to learn the meaning of a significant proportion of the language at the outset, but then you need to set it (and Duolingo) aside and instead get used to how the words are used in relation to other words in their own language.
Your number 2, bridging a language similar to the original is a good way to get things mixed up at the stage of having finished a Duolingo course. Sure, some people can do it and get some advantage for the first course from it. It is particularly good if you are interested in languages in general and just want to get to know a lot of them. It's even better if you are simply interested in the gamification aspects of Duolingo. But it's not going to help the language which you have just completed an essentially basic course in. (Essentially basic but with a number of decent nods towards intermediacy, in some cases.)
Your solution 1 is marginally better for developing further fluency. Using material with which you are mostly familiar, you will be asked to think a little more in the target language from the outset, and the majority of comments explaining things will be in that language - if you can be bothered to read them, but don't expect consistently decent examples of grammar or great prose. These are user-content forums, and as you might remember from some of the comments from the early stages of your normal direction tree, many of them may be quite nonsensical (including some of mine, but I was more than a touch ill at the time).
You have said "Be sure to keep all trees as golden as possible. " Sure, so long as you are using only Duolingo for your language learning, this is a decent minimum (although it can become a chore when translation meets pedagogical pedantry). I feel that it is better to abandon the Duolingo course tree almost entirely and instead use the time per day to read and listen to native texts and utterances.
On a sidenote, when you have finished the tree it is unlikely you have mastered the material therein. For a short time it is my opinion that you should continue with the more advanced verb (and declension) skills (and the like - the grammar stuff that Duolingo tries to hide from you) and simultaneously start the reverse tree (without much intent on really finishing it, but just to give you a little variety with some of the grammar lessons taken for granted while you are getting a better grasp of them from the normal direction Duolingo course tree). During this short time you should be willing to explore the language away from Duolingo - forget its streak counter and instead create something similar for yourself for having read/listened-to native material on a day.
With Duolingo, for Spanish and Portuguese, exploring Labs-Stories is a good start to head towards a more contextual experience of the language.
In accordance with these sentiments, I have given an upvote to the people who have recommended further materials (at time of writing: Actiregularis, 20Xray, NutinMikeHunt-69, InuzukaShino).
Where I have overstated anything, I apologise; I haven't slept well.
I personally would just practice the language over and over again, and try to keep it as golden as possible. From personal experience, I know that I would forget anything a couple hours after I learn it if I don't use it in my daily language. Keeping all those newly learned foreign language words fresh in your mind can definitely help with being fluent in that language!
Well.....you have a bunch of great answers here. However, I disagree with your first sentence. I don't think that finishing a "tree" is inevitable. Many, many people start and do not finish. In gigantic proportions I'll bet. Far more people get a little ways in and give up (for now). I wish you good luck, Ms. Nicole, on reaching your next level. Enjoy a Lingot.