I would start by checking the trans mount, make sure that it isn't soft and sagging. This can cause your problem. Crawl under the car and grab the tail shaft. if it can be moved by you, then it needs to be replaced. oil and tranny fluid leaking from the tail shaft can soften the rubber mount.

Next I would check the shifter bushings. you will need to crawl under the car and use a flashlight to look up on the top of the tranny housing. If you don't see any plastic bushings in the linkage connections then there is too much slop to shift into 1st or 2nd gear easliy.

Third involves removing the tranny and taking it's top plate off to look for a bent linkage or to adjust the linkage for wear.