I will probably come back to this question a little later (with lots of tips -or write a hub about it eventually) but first and foremost one of the biggest "mistakes" I see poets make, especially lyrical poets, is that their masculine rhyme is very predictable. They rhyme - just to rhyme! And the words they choose are typical and expected. In other words, they choose the very first or second word that comes to mind when they rhyme.
As a result it makes thier poetry very bland and mainstream and boring. You can test this against any poem.. take the first line in thier couplet or stanza and look at the masculine rhyme and then without reading the other line think of 3 words that rhyme with that last word and chances are it will be included in that next rhyme. Unless the entire poem is intended to blandly rhyme (like a Dr Seuss rhyme -and 'blandly' in this case is not a deragatory term, it is a purposeful rhymeing schematic) then poets ought to be more choosey about thier word choice. Words are the arsenal for a great poem.
Here is an example of what I'm taling about (that I just made up)
I once was in love
like it was sent from above (or, 'with a little turtle dove')
and all the angels did see
that love was intended just for me.(or, 'something something tree')
Now, with that said, it isn't wrong to choose the first or second word that comes to mind if the poem needs that particular word. But if a better word can be chosen that would still yield to the meaning of the poem then use it! And I'm not saying to make the poem difficult and take away from its' intended simplicity (if that is the case), I'm saying, be original. Study old poems and learn different poetic languages and meter.
So my tip is to be creative with word choice, learn new words, and stay away from expected rhymes. Read up on old poems and study thier meter, and thier word choice.