Generally, first and reverse is hard to get into gear.  Since they don't have synchro's.  My truck I have to RPM match the the gears to get it into first from second while moving.  And sometimes, I have to put it in Neutral and release the clutch to get it to fall into Reverse.

Sometimes its hard to get into second for me, but its usually because I don't have the clutch all the way in, or its cold out, and the trans hasn't heated up.