I do mow once in the spring and once before hot summer arrives. I've also found it very helpful to control grasses and weeds with herbicide. I read an online tip that you can use a diluted amount of roundup (glyphosate) which kills the grasses but only stuns the clover. I tried and it works great. Grasses and weeds die, clover comes back strong. I use 1 1/2 oz per gallon of water, spray it with an atv sprayer, and apply it about 2 weeks after I've cut field. If it's really dry, I wait until after we've had some rain and everything is growing well. I also give clover a shot of 0-20-20 fertilizer in the spring.
Keep in mind it takes about two weeks before you see the grasses and weeds turn brown so be patient. You will have to spray more than once, just use your own judgment on how often and when based on how your field is doing.