Answer: Since you are a new gardener I think you are dealing with a number of issues here. First off, the best way to start planting is to prepare an entire general area by removing any existing weeds or grass, then working in some organic matter such as compost, or old leaves or aged manure about a month before planting. Once you have placed the plants in the ground, water each one generously and then surround it with a few inches of organic mulch such as shredded bark. This will help keep weeds from growing and outcompeting your desired plants.Just make sure the mulch doesn't touch the stems of your plants, or it may cause rot.
To grow tulips, you would plant the bare bulbs in the fall. The next spring the tulips would sprout and bloom and then grow leaves. Eventually the leaves will wither and die. This signals that they have replenished the bulb, which should flower next year. If this is what happened to your tulips, then the bulbs may still be there underground and will probably bloom again next spring. In general, tulips don't blossom well after the first couple of years unless you give them special treatment. Daffodils and crocus, on the other hand, will multiply quickly if you mulch them with an inch of good compost each spring.
Starting plants from seed sown directly in the garden can be a bit more of a challenge. If you want to try some seeds this way, you might consider some of the easier annuals such as marigolds, nasturtiums, or zinnias and then move on to the more demanding plants. In general, after the last average frost date, plant the seeds in soil prepared as above, water them and keep the soil moist but not sopping wet. Once seeds they germinate, keep them weeded and mulched.
When planting, keep in mind the ultimate mature size of the plants you are using. Plant accordingly so that the plants will not be too crowded. Most labels and seed packets will tell you how large the plants should get so you can figure out the right spacing.
Finally, with regard to fertilizing, yes it is a good idea to fertilize your plants according to the label instructions especially if your soil is not too rich. If flowering plants get too much fertilizer (especially nitrogen) they grow great leaves, but won't bloom. Many gardeners find the water soluble fertilizers such as Miracle Gro very satisfactory. However, fertilizer is not a substitute for proper planting and soil preparation. In fact, fertilizer will help the crabgrass grow just as it helps the desirable plants grow!
If you want more general information on planting a flower garden, you might find "Annuals for Dummies" by Bill Marken or "Gardening for Dummies" by Michael MacCaskey helpful. Both books are full of straightforward information in a fun format, describing how to prepare the soil, selecting plants and caring for them.
Enjoy your garden!
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