A general plea to all: please do not ever publish, recite, or tattoo(*1) a Latin phrase you got from an automated translation on the internet. Those programs are not nearly clever enough yet to understand Latin morphology or syntax, and will invariably spit out either complete gibberish or something wholly unlike what you intended. It makes Classicists cry inside, and then our insides mildew.
As for the phrases, it would depend what sort of Latin you wanted. A purely mechanical translation of the English would be comprehensible, but probably wouldn't be anything a Latin author would actually write. To arrive at an authentic sounding Latin phrase, you would need to pull and stretch at the meaning a little.
NighSwan mentions that classical Latin tends towards a minimalist aesthetic, which is very true. Latin loves to omit what we would consider essential syntax and force the reader to supply what is implied by the surrounding context. In that spirit, one possibility would be:
Tuis quod possis.
A literal translation of only what is explicitly phrased there would be "With your things, what you can". Supplying the omissions, a clumsy translation would be "(do) that which you are able (to do) with (those things which belong to you)". It is almost as vague in Latin as it sounds in English, but is rather elegant at the same time, employing homoioptoton and the "sandwich" construction Roman authors were so fond of.
More literally, "Do the best with what you have" could perhaps be rendered as "Optimum fac quo tibi est". Literally this means, "do the best (thing) with (that which) exists for you". (Note that Latin does not typically express possession with the verb "to have", as suggested elsewhere, preferring what is called the possessive dative construction; rather than saying "I have a house at Baiae", a Roman would say, "there is a house at Baiae for me", and mean the exact same thing).
The above uses the imperative form of the verb used for "do/make", however, which may not be quite what you wanted. A slightly gentler way of expressing the idea could be "optimum facias quo tibi est", which expresses more of a wish than a command: "May you do the best with what you have". Such subtle shifts in meaning are a feature of Latin, which is one reason why I suggest caution with anything automated.
Another distinction for your second phrase is possible by using a double accusative with facio. If you were to write "optimum facias quod tibi est", the meaning shifts to making x into y, rather than doing x with y. Literally: "May you make the thing which you have into the best possible thing", or more loosely, "make what you've got the best," not just "make it the best you can". You could also use fac in place of facias in that phrase to get an order in place of a wish.
There are a few suggestions. As I say, though, it depends on exactly what you want the Latin to look, feel, and sound like.
(*1) - You should see some of the hilarious Latin I've seen permanently inked on people's bodies. Why do people rely on Google to translate words they were going to burn into their living flesh?
to Nualláin for the cool idea and to CB for the righteous words.
